Thanks for joining me for the commentary. The match report is now up on the site and reaction will follow.
Full Time. Southampton hold on for a vital 2-1 win.
But the offside flag is up following the cross and the chance is gone.
Shaw with a foul. Last chance.
Rodriguez almost finds a way through Terry and Ivanovic but Cech is off his line to clear.
Lampard curls the ball over the bar.
Hazard fouled in a dangerous position. Chance here.
86 Fox on for Davis.
Moses has men in the box but cannot find a way past Shaw.
84 Lambert booked for timewasting.
Melee in the Saints box after a low cross by Azpilicueta but the home side clear.
Chelsea pushing hard for the equaliser now.
Lampard almost plays Moses in down the left but Clyne does well to force him wide.
Lampard sees a free-kick blocked.
Brilliant run from Hazard as eludes several challenge and then fires the ball across the area. Nobody on the end of it though.
77 Benayoun on for Oscar.
76 Torres booked for an aggressive aerial challenge on Yoshida.
Wonderful Southampton move down the right sees Clyne get to the byline but nobody can get on the end of the cut-back.
73 Ramires on for Mikel.
Schneiderlin puts Ward-Prowse away on the counter-attack but the latter cannot find a Saints shirt with the cross.
Torres stabs a pass through to Moses. He is one-on-one with Yoshida but cannot find a way past his marker.
Hooiveld heads wide.
Shaw wins the corner with a driving run.
Penalty claims as Moses goes down under a challenge from Yoshida. He went down a little easily after the defender stepped across him.
Rodriguez is through again but his touch lets him down.
Chance! Rodriguez creates the opening for himself after nicking the ball away from Ivanovic down the left channel. He shoots left-footed but Cech saves.
Chelsea corner taken short and Oscar then blasts the cross out of play. Terry disgusted.
Davis clips the ball to the near post and Rodriguez gets there first but he has got too much on it and it's out of play.
Terry tries to head the ball back to Cech but instead concedes a corner.
63 Ward-Prowse on for Puncheon.
62 Marin replaced by Hazard.
Terry does well to tackle Puncheon but is then robbed and Cork shoots recklessly when he had options.
Chance! Torres takes a quick free-kick and Moses seizes on the cut-back from Azpilicueta. The effort looks set to loop over Davis but he just gets a hand to it.
Marin tries to latch onto a long ball but Davis off his line well to claim.
Clyne crosses but it is overhit.
Moses outmuscles Shaw and gets the ball to Lampard in space. He spreads the play to Marin on the left but Clyne blocks his shot.
Southampton fail to clear and Marin gets a second chance to cross. It falls nicely for Moses but he can only shovel the ball out to Lampard who is offside.
Moses wins a corner off Shaw.
Quiet spell now as the teams trade possession in midfield.
Marin puts Bertrand away down the left. He is in space but it is an awful cross and easily cleared.
Cross comes in but it is headed wide.
Davis whips the ball in but Chelsea clear. Then Clyne attempts a cross-shot and Cech parries for a corner.
Poor clearance from Cech and Southampton are almost in again. The ball will not quite fall to Schneiderlin after good work by Shaw and Rodriguez.
Southampton kick-off and we are underway.
46 Boruc is injured and has been replaced in the Saints goal by Kelvin Davis.
Thanks for your feedback. The players are back out and we're about to get underway.
Michael: "Bring Hazard on. We need that injection of pace and he provides that. And maybe Ba for Torres."
Sky Bet have the latest odds. Can Chelsea turn things around after the break? They are 5/1 to win now with Fernando Torres the 6/1 favourite to score next.
Richard: "Looks like the mighty Saints are putting on a great show."
Samuel: "Rodriguez starting to prove his worth now."
Glenn: "Lots of Chelsea fans slating the team selection but that team should be good enough to beat Southampton. Time to look to the players."
Half Time. That's the end of the first half and Southampton hold a deserved 2-1 lead. Benitez needs to change this as their grip on a top-four spot is loosening. Pochettino will surely just want more of the same.
Rodriguez almost latches onto a long ball from Hooiveld but cannot bring the ball down.
It's slightly overhit but Southampton retain possession. They're camped in the Chelsea half and looking to double the lead.
Southampton win a corner.
Rhys: "Following on from what so far Chelsea have done, take off Moses and Mikel, bring on Hazard and Luiz. Furthermore, in the summer bring back Mourinho and sign Falcao, ditch Torres and recall Lukaku."
Southampton utterly dominant at the moment and almost showboating. No response from Chelsea right now.
Lambert just ruled offside although Cech saved the follow-up effort from Rodriguez anyway.
Clyne with the cross to Lambert at the far post but it is too close to Cech and the keeper claims.
Southampton still attacking and Rodriguez sees a fierce shot blocked.
Simon: "Mata is the engine, Hazard is the wheels and without them this is what we're left with..."
Lambert whips the ball over the wall and into the net with Cech beaten. Torres slightly broke away from the wall but it was perhaps just over his head away. Lovely strike.
35 Goal! Rickie Lambert!
Free-kick to Southampton in a good position.
Marin with the outswinging corner from the right and Hooiveld slips allowing Terry a free header. He makes no mistake and Chelsea are level.
33 Goal! John Terry!
Chelsea pushing now and Moses sees his cross deflect off Shaw and just over the bar for a corner.
Long ball almost reaps dividends for Southampton after Lambert wins the flick on but Terry manages to hook the ball clear.
David: "What a pathetic performance so far from the Blues and all down to shocking team selection - come on Roman, sack Benitez at half time."
But it comes to nothing.
Bertrand wins a corner for Chelsea.
Torres has the ball in the net but he is ruled to have handled the ball. He did and it wasn't really necessary to do so in order to get away.
Rodriguez on the left edge of the penalty area and he plays a sidewards pass to Davis then dart in behind the defence. Davis finds him with a first-time return pass and Rodriguez calmly slots the ball past Cech.
24 Goal! Jay Rodriguez!
Torres does lay the ball off well this time but Oscar cannot find Bertrand down the left and the move breaks down.
Southampton retaining the ball well without getting too far up the field.
Arsenal and Tottenham both winning at the moment so plenty of pressure on Chelsea here.
Torres not getting a great deal of support at present and struggling to hold the ball up.
Corner is overhit and Moses is then fouled by Cork as he tries to bring the ball away.
Several chances to whip the ball in but Chelsea get the ball away until Lambert wins another corner.
Good run from Clyne wins a corner.
Southampton just about on top and causing more problems but it's a fairly open game.
Rodriguez with a powerful run down the left but although he beats Terry, who commits early, the ball runs through to Cech as his touch is too heavy.
Puncheon's cross headed away by Terry.
Corner for Southampton after Lambert's shot is blocked by Ivanovic.
Promising attack from Saints as they get plenty forward but Puncheon twice spurns openings. Firstly, his cross cannot find a home shirt and then he forces his way past two men in a central position before the ball is cleared.
Marin with the ball in but he cannot beat the man at the near post. Southampton break through Rodriguez but he attempts a sidefooted finish from 20 yards and there isn't enough to pace on the ball to beat Cech from there.
Puncheon shows good strength to win the ball on the left but nobody can get on the end of his fizzed cut-back. Chelsea go straight up the other end and win a corner.
But it comes to nothing as Southampton clear.
Chelsea win a corner after good work by Moses and Oscar.
Azpilicueta gets forward for Chelsea and the ball comes out to Moses in space but the winger overhits the cross.
Patient build-up from Southampton almost backfires as Yoshida's pass is intercepted by Marin but the Chelsea man cannot control the ball.
Now Lambert tries to put Rodriguez through with a flicked pass but Cech is comfortably off his line to claim.
First chance of the game and it comes from a long diagonal from Saints. Hooiveld finds Lambert and Rodriguez fires the knockdown over the bar under pressure.
Lampard hooks the ball forward for Moses to chase but Boruc is off his line to intercept and Southampton get their first touch of the ball.
Chelsea kick-off and we are underway.
Warm embrace between Pochettino and Benitez.
Thanks for all your feedback. The players have emerged from the tunnel at St Mary's and we'll be underway shortly.
Juan Mata is the only Premier League player to reach double figures for goals (10) and assists (10) this season. Meanwhile, Eden Hazard has had a hand in six goals (four goals, two assists) in his last seven Premier League appearances for Chelsea. Neither man starts today.
David from Sydney says: "Think the Spanish waiter is underestimating Southampton with his team selection! Won't be surprised if the Blues surrender a goal or two and fail to register one themselves."
And only three players have created the most goalscoring chances from open play in the top five European Leagues than Rickie Lambert (62).
In terms of key players for Saints, Morgan Schneiderlin has made more tackles (121) and interceptions (112) than any other player in the Premier League this term.
Chris from Huddersfield says: "Chelsea will probably win this game today, but it would be lovely if Southampton caused a major shock. My head says 3-1 to Chelsea but my heart says 2-1 to Southampton."
But Southampton shouldn't be too disheartened. Chelsea have conceded a league-high proportion (70%) of their goals in the second half of matches this season.
The visitors will be looking to start this game on the front foot - Chelsea have scored the first goal of the game on 19 occasions this season, a Premier League high.
Jake: "I think an easy win for Chelsea. Torres needs a goal."
Sky Bet are reporting that the line-ups have impacted on the betting. Chelsea are struggling to find support today and have drifted out to 5/4 while Southampton are 21/10 to boost their survival hopes with a win. Fernando Torres leads the line for the Blues and is 9/2 favourite to score first ahead of Rickie Lambert (6/1).
After netting his 200th Chelsea goal in his last match for the Blues, Lampard is only two away from Bobby Tambling's all-time Chelsea goal record (202).
Frank Lampard, in particular has enjoyed himself against Southampton, has scored four goals in his last four Premier League appearances against today's opponents.
Chelsea have a good record against Southampton - they are unbeaten in their last seven Premier League games against them (W4 D3).
Rich: "I'm worried about Chelsea today without two of the three amigos and with Torres playing. Could be close. Southampton 1-2 Chelsea."
Ben: "Should be a tough game but the Reds can pull through. 2-0 for Saints."
Callum: "Southampton to win 3-2. Schneiderlin, Rodriguez and Lambert to score."
Terry makes just his second Premier League start under Benitez.
Two changes for Saints. Puncheon and Davis in for Ramirez and Lallana, who is out of the squad with a groin problem.
Southampton: Boruc; Clyne, Yoshida, Hooiveld, Shaw; Schneiderlin, Cork, S. Davis; Puncheon, Lambert (c), Rodriguez. Subs: K. Davis, Fonte, Ramírez, Fox, Forren, Ward-Prowse, Guly.
Chelsea: Cech; Azpilicueta, Ivanovic, Terry (c), Bertrand; Mikel, Lampard; Moses, Oscar, Marin; Torres. Subs: Turnbull, Cole, David Luiz, Ramires, Hazard, Benayoun, Ba.
Unfortunately for Nick, Mata won't be among the goals today. He's not in the Chelsea squad. Team news coming up.
Nick: "I can see this being a tricky game for Chelsea. I'm hoping for a 3-1 win though. Mata. Lamps and Ba with the goals."
Ashley from St. Albans says: "2-1 Southampton. Lambert brace."
Adam says: "Going to be a tough one for the Blues. I think a scoring draw looks a good bet."
Any predictions ahead of this one? Let me know by email at email@example.com or on Twitter @GhostGoal.
Our friends at Sky Bet rate Chelsea as the 23/20 favourites for this one with hosts Southampton as the 23/10 underdogs. The draw is available at 12/5.
Southampton's safety is far from certain as they are just four points above Wigan in 18th and the Latics have a game in hand going into the weekend. A win here would ease relegation fears.
Chelsea need the points as they look to hold onto third spot and secure Champions League football next season.
Welcome to live commentary of the Premier League clash between Southampton and Chelsea from St Mary's.
Updates will appear here...