It's the oldest cliché in the book but the Hatters now have the league to concentrate on after a stunning first-half free-kick from Richie Lambert ended their run in the FA Cup at St. Mary's.
Despite the 42 places between the two sides in the pyramid, the Town performed admirably against Alan Pardew's Saints, especially in the second period.
Lambert's superb curling free-kick from 35 yards was the difference in the end but a clutch of missed chances from the Hatters in the second half will leaving them wondering what might have been.
Their best chance fell to Adam Newton on 57 minutes when he somehow missed his kick from two yards out with the goal gaping following good work down the right flank by Claude Gnakpa.
While the Saints had the best of the chances in the opening period the Hatters turned the screw against their lofty opponents but couldn't break find what would have been a deserved equaliser.
Full report to follow.
For minute-by-minute analysis, see below:Full time from St Mary's
Southampton 1 (Lambert 36)
Luton Town 0
FULL TIME - SOUTHAMPTON 1-0 LUTON TOWN - It's all over here at St Mary's and the Town's FA Cup run is over for another season. We'll have all the reaction to come.
90 + 1 mins - We've got four added minutes as Lallana flashes a mis-hit shot into the side netting to further frustrate the home support.
90 mins - We're into the final minute - will the&nbsp;Hatters get one last chance?
87 mins - Those that have impressed for the Town this afternoon include Hall, Nwokeji, Kevin Pilkington and Asafu-Adjaye who has done really well at right back.
86 mins - More Hatters pressure as Hall does well again in the centre of midfield and feeds Gnakpa who tries his luck from 25 yards with a shot that just sails over the crossbar.
82 mins - More good play from the Town as they hunt a late leveller. Hall sends Craddock scampering away down the left but after beating two men he can't beat a third as they home defenders beging to converge on him. Moments later Jarvis floats a free-kick deep into the Southampton penalty box that Gnakpa gets a head to but his effort narrowly dips the wrong side of the crossbar.
78 mins - Saints fans are getting restless&nbsp;but they come close to making it 2-0 with two chances in the space of a minute. Firstly substitute Paterson fizzes a shot a whisker away from finding the corner of the net before Schneiderlin heads straight at Pilkington from Papa Waigo's right wing cross. The Town have 10 minutes left...can they do it?
77 mins - Decent half chance for the Hatters as&nbsp;a quick-thinking Hall plays a free-kick into the path of Craddock but the striker has the ball on his left side and can only shoot wide of the target with Davis at full stretch.
76 mins - The official attendance has just been shown to the press pack. 18,786 including a magnificent 3,017 shouting for the Town.
75 mins - Time running out for the Town but the change has seen Watkins play down the right-wing with Claude moving to the left.
73 mins - Third and final change for the Hatters as Adam Watkins comes on for his senior debut for Newton.
67 mins - Pardew has introduced Matt Paterson for Antonio and his first action is to tee-up Lambert who is lurking on the edge of the area. However, the goalscorer gets his shot all wrong as he attempts to bend one into the top corner, the ball instead is screwed well-wide.
66 mins - Even-steven now but the Town are still enjoying the better of the ball. Craddock does well to fend off the attentions of his marker to send a low cross towards Nwokeji but Harding is on hand to clear the danger and Saints are let off the hook again.&nbsp; The Hatters have grown in stature and confidence this half.
59 mins - St. Mary's is absolutely buzzing - with the sound of the travelling Town fans who are making are right racket behind the goal. Their support is being rewarded on the pitch and the players are responding. Can they get one their play has deserved in the opening 15 minutes of this second period?
57 mins - Unbelievable. Should be one a-piece. Newton is left red faced as he fails to tap home, missing his kick at the back-post with the goal gaping following good work between Gnakpa and Nwokeji down the right. Newton retrives the situation by squaring the ball to an unmarked Nwokeji but the substitute can only drag his left-foot shot agonisingly wide of Davis' left-hand post.
54 mins - The Hatters are giving their 3,000 fans something to shout about now as they are well on top playing some really good stuff with Nwokeji looking very lively. Can they grab and equaliser? A fine start to this half, COYH!!
50 mins - That early scare as woken the Town up and how. Jarvis robs Schneirdlin for the ball 40 yards out finds Nwokejo who races goalwards. His pace is frighenting the hosts already. He drills a shot is blocked but the rebound falls to Hall who lets fly with a well-hit shot from 25 yards that Davis does well keep out. Much better.
46 mins - 13 seconds into the second half and it should be curtains. The Town defence are caught half asleep but with the goal gaping and time on his side Antonio can only shoot straight at Pilkington from 12 yards. What a let off.
46 mins - We're under way for the second half. We've got two changes to tell you about for the Town as Mark Nwokeji and Claude Gnakpa are on for Kevin Nicholls and Kevin Gallen.
HALF TIME - Southampton 1-0 Luton Town - A fabulous strike from Lambert is the difference between the two sides. Check back in 15 minutes for the second half updates. COYH.
45 mins - We've got two additional minutes to play at the end of the first half.
42 mins - Great chance for 1-1. Asa Hall plays a delightful pass into the path of Jarvis who fires a shot from the edge of the area that has to be beaten away by Davis. With Craddock sniffing for the rebound the Hatters win a corner but the Saints are able to clear the danger. Great play. Unlucky.
40 mins - The Town are trying to get back in this but the Saints' tails are up. Lallana and Antonio combine well down the right which sees the striker twist and turn in the box and fire a shot across goal that is collectly bravely by Pilkington.
36 mins - GOAL - SOUTHAMPTON 1-0 Hatters - The Town go behind to a stunning 35-yard free kick from Lambert, curling the ball in the top corner of the net but the Hatters are quite rightly unhappy after Lallana looked to have gone down far too easily under a challenge from Nicholls. Richard Money's not happy but ut was one helleva strike. It had been coming. But we've been behind before in this competition at Rotherham, so it's not over yet.
29 mins - Brief respite for the Hatters as the Saints mount another attack which sees Papa Waigo go close at the back stick following more tricky wing play from Antonio down the right.
28 mins - Back come the Town as Gallen heads a decent half chance into the gloves of Davis following Howells' left-wing cross.
27 mins - The Hatters are really under the cosh and should be behind. Morgan Schnederlin sees his effort cleared off the line - not quite sure who by to be honest. The ball even looked like it had gone over the line. We'll update you on that, It was close. Very close.
25 mins - Pilkington - Kevin that is - is at it again. Asafu-Adjaye fouls Lallana 30 yards from goal and is booked for his troubles. Lambert - who has scored a terrific goal for Bristol Rovers against the Town in the past - fancies his chances. He hits a super free-kick that sails over the wall and looks destined for the top corner until Pilkington flings himself to the top corner to push away the shot. Great effort, great save.
23 mins - It is very cold here at St Mary's - so apologies in advance for any typos - but Richard Money is dressed for the occasion - bobble hat and socks pulled up to knees - nice look!
21 mins - Pilkington's called into action for the second time and needs to be at his best to push away Antonio's shot from just inside the penalty area after the winger, on-loan from Reading - had beaten Jake Howells to the&nbsp;ball. As the ball ran free George Pilkington was the first to the ball to clear the danger. Still 0-0.
17 mins - That chance by Lallana probably the best opening so far but Saints skipper Dean Hammond should do better when unmarked to&nbsp;head a Michail Antonio corner goalwards that is cleared by Newton.&nbsp;
14 mins - Great terrace banter from the Hatters hordes as they goad the home support with chants of Play up Pompey...
11 mins - Snapshot from Gallen from 25 yards but Davis is equal to it, diving down to left. Saints on top now, though.
9 mins - Southampton coming into this now. Lambert, who cost&nbsp; a &pound;1m from Bristol Rovers in the summer does well to turn in the penalty area but his pass is cleared by Adam Newton and then the hosts force Kevin Pilkington into his first save of the match, getting down well at his near post, diving to his right to keep out Adam Lallana's close-range shot following Papa Waigo's cross.
4 mins - More good play from Craddock, down the left beats the Southampton defence leaving them flat-footed by is short of support. Kevin Gallen is in their but his strike partner cant pick him out as Davis parries away the cross, Encouraging play from the visitors.
3 mins - Bright start - much like the January sunshine - by the Town. Tom Craddock takes a pass from Rossi Jarvis but can't pick out&nbsp; team-mate.
1 min - We're off as the Town get us underway kicking towards Kelvin Davis' goal - the stand behind that goal is completely closed to supporters with only what looks like the Saints' youth team watching high up.
14:58 HERE THEY COME
Absolutely barnstorming reception for the Hatters from the 3,000-strong contingent behind the goal. The Town are in their now traditional orange shirt, white shorts, and orange socks. The Saints are in their usual red and white shirts and black shorts.
14:56 MULTIBALL - YOU'VE BEEN WARNED
The stadium PA announcer has informed the St. Mary's crowd that the referee has given the Saints the green light to deploy the multi-ball system. You must give the ball back straight to the ballboys and not throw it back onto the pitch!
14:54 THREE THOUSAND
We sold 2,000 tickets in advance and I'm pretty sure the extra 1,000 available on the day to Town fans have been snapped up. The Hatters fans are in top, top voice, COYH!!
Sorry I haven't updated you over he past half an hour. I'll call it "technical difficulties". I'll attempt to open the emails later so apologies&nbsp;if you've emailed in and not seen your message yet.
14:22 THREE CHANGES
Hatters boss Richard Money makes three changes to his side with Shane Blackett,&nbsp;Ed Asafu-Adjaye and Asa Hall in for Claude Gnakpa, Matthew Barnes-Homer and Keith Keane.
With seven substitutes to name, Money names&nbsp;17-year-old defender Alex Lacey is on the bench alongside two other youth products Jordan Patrick and Adam Watkins.
Alan Pardew names two ex-Luton players in his starting XI in the shape of goalkeeper Kelvin Davis and defender Chris Perry with &pound;1m striker and leading goalscorer Rickie Lambert in attack.
Luton Town: K. Pilkington, G.&nbsp;Pilkington,&nbsp;Asafu-Adjaye, Howells, Nicholls, Hall, Jarvis, Newton, Craddock, Gallen.
Substitutes: Gore, Gnakpa, Nwokeji, Watkins, Patrick, Lacey, White.
Southampton: Davis, James, Perry, Thomas, Harding, Antontio, Schneiderlin, Hammond, Lallana, Papa Waigo, Lambert.
Substitutes: Bialowski, Lancashire, Wooton, Holmes, Mills, Gobern, Paterson.
14:00 PITCHSIDE REACTION
I've just been pitchside and the pitch is quite hard, especially half of the pitch that has been in the shade. It's brilliant sunshine and clear blue skies. A beautiful setting for what promises to be a fantastic afternoon's entertainment.
Speaking to a few of the players they think the pitch is a bit too hard! However, Richard Money, who has just spoken live on BBC Radio 5 Live, believes the pitch is in top condition.
Trondheim Hatter: I'm predicting the game to end 0-0 and a televised replay at Kenilworth Road!
Chris Luke: This new concept is&nbsp;a great idea, chance to get more involved, have ticket for today's game but a really bad cold keeps me from going...I predict a 'semi shock' 2-2 draw to&nbsp;give us a&nbsp;chance of more revenue from a home replay.
13:00 DO THEY KNOW SOMETHING WE DON'T?
According to&nbsp;BBC Ceefax and the BBC website the Hatters' goalkeeper Lewis Emanuel is expected to play before going for a operation on Monday...Should make for an interesting 90 minutes.
It's cold down on the South Coast. A few Town fans have already arriveed and are milling around the magnificent St. Mary's Stadium.
I've just bumped into Chairman Nick Owen who is in typically high spirits. We're all asking ourselves the same question: Can the Town do it today? Send us your predictions!
Good morning and&nbsp;welcome to lutontown.co.uk to our text updates service as the Hatters travel to Southampton for an eagerly-anticipated FA Cup third round clash at St Mary's.
Alan Pardew's men have been in fine form in League One this season but are feeling the force of 10-point deduction which has prevented the Saints from finding themselves in the play-off places.
It therefore means it's another tough test for Richard Money's men but this competition has already seen off two Football League sides doing well in League Two and the Town don't want to stop at just two shocks - they're going for the hat-trick.
Today will be the Town's sixth tie in the competition. A routine win over Grays Athletic in the fourth qualifying round has been followed by fine victories over Rochdale (2-0 in a replay after a 3-3 draw) and Rotherham (3-0 in a replay following a 2-2 draw).
Southampton will be looking to dodge the bullet of being put out by one of the four Blue Square Premier sides that remain in the competition but the cup has brought out the best in the Hatters over the past 12 months, especially when tackling oppostion above them in pyramid.
A 4-1 win over Eastbourne Borough on Monday has blown away some cobwebs that 16 days without a game brought over the festive period and a trip to the South Coast to a stadium that was gracing the Premier League not too long ago will also see over 2,000 Hatters fans in attendance.
If you're going - have fun and remember to get in touch if you are, as we're looking for your input in&nbsp;our new matchday live experience.
If you can't make it, then fear not: at&nbsp;lutontown.co.uk we'll have all the usual updates keeping you bang up-to-date with all the action - and in a number of ways.
There's none of those boring ball-by-ball "defensive thrown-in taken by Luton left-back" updates as we continue to try and bring you an updated and detailed text commentary. This is a great way to keep in touch and has been popular to those supporters not able to get to a computer or a radio as the service is also available and is updated live on our WAP site.
On Hatters Player you all have access to our live commentary. Remember, Player is available as ever which means you all have access to our live commentary. If you haven't heard it yet then where you have been? It's brought to you by Simon "Statto" Pitts - who is quickly making a name for himself with commentary that is the envy of all the competition.
We're once again grateful for our counterparts at Southampton for allowing us to use their facilities to enable the DiverseFM and Luton Town media partnership to broadcast around the globe on Player.
Of course after the action has finished, Hatters Player will have all the post-match interviews from all the men that matter today.
Whether on Hatters Player or not, we'll have plenty of content to keep you interested as we'll have all of the post-match reaction as well as match action from Gareth Owen to follow after the final whistle. Be sure to check out www.hatterspics.co.uk - our brand new online image library.
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Enjoy the game.