Southampton V Chelsea - As it happened
FT: Southampton 2 - 3 Chelsea - A huge second-half turnaround from Chelsea sees them take all three points. Southampton extended their lead to two goals early in the half, but this is what it took for Chelsea to switch on. Olivier Giroud came off the bench to score a brace, his two goals sandwiching a lovely finish from Eden Hazard. Southampton will be gutted, after throwing away a two goal lead that would have dragged them out of the relegation zone.
Another card. This time it's Gary Cahill, who clatters Shane Long. The free-kick is crossed in, but Courtois leaps and holds.
The home fans think that Austin is in on goal, and a cheer of excitement fills the stadium, but he's offside.
Gabbiadini comes on for debutant Bednarek. Three minutes to find an equaliser.
There will be five minutes of added time for Saints to find an equaliser.
Close! Hojbjerg heads from just near the penalty spot after Bertrand's corner found him in space, but Courtois catches.
Final change for Chelsea. Victor Moses replaces Eden Hazard, in a move intended to sure up the defence for Southampton's final onslaught.
Dusan Tadic comes off, after a strong performance, and Sims comes on to replace him. 10 minutes to find an equaliser.
Amongst all the action there have been a series of yellow cards. Shane Long, Romeu and Willian all go in the book.
GOAL! Chelsea! Giroud! Yes they can! What a turnaround from Chelsea. Willian gets a free-kick and plays a sly ball to Hazard, instead of crossing. The Belgian crosses, and Azpilicueta and Cahill both have attempts at heading it in. There's a bit of pinball and it falls to Giroud just outside the box, who hits it low through all the bodies, past McCarthy. Southampton are shellshocked. Mark Hughes is gutted. Massive collapse from the home side.
GOAL! Chelsea! Hazard! And they've levelled it! Two goals in five minutes for the visitors, who have switched on since the second Saints goal. Willian receives it on the wing, and puts a lovely low cross behind the back line. Eden Hazard is there in the box and absolutely buries it in the top left corner. There's no saving those. 2-2 now, can Chelsea complete the turnaround?
Hoedt needs treatment after clashing heads with Giroud as he headed home. He's back on his feet though.
GOAL! Chelsea! Giroud pulls one back! French magic! The big forward scores from the bench with a powerful header past McCarthy. The goal was created by Marcos Alonso, who put a lovely early cross in down the left. Can the visitors claw it back?
And now Ryan Bertrand sees yellow for impeding a Chelsea throw-in. What a bunch of children.
Eden Hazard is shown a yellow card for shoving Hoedt at a Southampton throw-in.
Double change for Chelsea in response to the goal. Zappacosta and Morata come off, and on come Giroud and Pedro.
GOAL! Southampton! Bednarek! What a massive goal from the defender on his PL debut! James Ward-Prowse delivers a lovely free kick, bending it to the back post. The ball falls on a plate to Jan Bednarek, who slots it coolly past Courtois on the volley to make it 2-0. Great finish, what a way to mark your debut.
Chelsea push for a goal at the other end, and come close through Hazard. The Belgian wins a corner, and Willian strikes it from outside the box. The rebound falls to Hazard, who nearly puts it in, but it's offside anyway. Close.
Shane Long nearly goes it alone! The Irishman does well to get on the end of a long ball, controlling it superbly and heading towards goal. He appears to be dragged down by Christensen, in a potential penalty shout, but he gets up and carries on. He cuts back and strikes, seemingly slipping halfway through, and Courtois is forced to make a good save.
Olivier Giroud is warming up for Chelsea here. Can a bit of French magic change Chelsea's fortunes?
CLOSE! Ward-Prowse whips a good cross in from a corner, and Yoshida gets on the end of it. He can't steer it goalwards though, and he may have injured Courtois in the process of trying to.
A nice attacking move from Chelsea ends with a shocking finish from Morata, who skies it from 25 yards out.
Southampton get us underway for the second half.
HT: Southampton 1 - 0 Chelsea - A fairly lowkey half ends with the home side in front. Chelsea have been okay, but Saints just seem to want it more, and deservedly lead through a Dusan Tadic goal, scored in the 21st minute. Chelsea have had 7 shots, but none of them have been on target.
And now Ward-Prowse sees yellow after clattering into Willian. Meanwhile, Shane Long is being seen to by the medics after he was trodden on by Alonso. He's okay to continue, though.
Yellow card for Hojbjerg after a late challenge on Zappacosta.
Saints get a free-kick after Christensen collides with long. Ward-Prowse delivers it from 30 yards out, and Yoshida gets a head to it, but he can't get it on target and it flies wide.
CLOSE! Shane Long controls a long ball, who heads towards goal. Azpilicueta intercepts, but it falls to Ward-Prowse. The Englishman shoots and Courtois parries. The ball falls to Tadic, but he can't get enough power on it. He's offside anyway.
Gary Cahill charges forward. He sees the space opening up in front of him. He looks up. He sees his name in lights. He strikes a piledriver from 30 yards out...and it's high and wide.
Morata is equally frustrated when another tussle is blown for a foul, but this time in favour of Southampton. The Spaniard had gone for a header, but caught Yoshida in the face with his head. Nothing in it really.
Christensen charges out of defence to intercept a ball, playing it forward to Morata. The striker is brought down by Yoshida, who got a bit too tight, and Morata is furious. Mike Dean tells him to calm down in typical Mike Dean fashion.
The visitors maintain the pressure, and earn a series of corners. Christensen should score from the third, as he finds himself free at the back post, but he mistimes it and misses the ball.
Chelsea string together a good attack, after Eden Hazard is found down the left wing by a well-weighted cross-field ball. He lays off to Kante, who puts in a cross to the back post. Zappacosta nods it back across goal, but it's too weak for Morata, who ends up heading over the bar.
GOAL! Southampton! Tadic! First blood to the home side, after some good work from Ryan Bertrand. The left-back makes a powerful run down the wing and into the box, and Azpilicueta can't catch him. He cuts it across for Tadic, who sweeps it past Courtois. Exactly what they needed. 1-0.
A good combination between Hazard and Morata sets up a Chelsea attack, but Marcos Alonso is hacked down for a foul. Willian delivers from 30 yards out and Morata is just inches from turning it in. McCarthy claims it.
Southampton have had a few decent chances and are keeping things tight. Chelsea look a threat on the counter, though, and Willian comes close. He breaks down the right, but his cross is too close to the keeper and McCarthy collects.
Hazard makes a lively run into the box and completes a one-two, but Willian is unable to latch onto the final ball.
Although both sides have employed a five-man defence, it is clear early on that Southampton are going to be using a 5-4-1 to defend against Chelsea, who are more attacking in a 3-4-3. Chelsea are on the front foot early on, but Saints look capable of a counter, and fly down the left through Bertrand twice.
And we're off! Chelsea get us underway at St. Mary's.
The players are out on the pitch here, as kick off approaches. Southampton in red and white, with Chelsea in their iconic blue.
Southampton really need to pick up points here. They are currently 18th, three points below Crystal Palace with a game in hand. A win would take them 17th, until Palace play later today. Chelsea, meanwhile, are fifth, ten points behind fourth-placed Tottenham. They need a win to have any chance of making the top four.
Jan Bednarek receives a PL debut for Southampton today, replacing Jack Stephens in the back three, after Stephens received a suspension against Arsenal. Both sides are employing a five-man defence, with Morata and Hazard leading the line for Chelsea. Ross Barkley is back in the squad after recovering from injury, but he starts on the bench.
And the visitors' side: Courtois, Azpilicueta, Christensen, Cahill (C), Zappacosta, Kante, Fabregas, Alonso, Willian, Morata, Hazard.
Here's the home side's first XI: McCarthy, Cedric, Bednarek, Hoedt, Yoshida, Bertrand (C), Romeu, Ward-Prowse, Tadic, Hojberg, Long.
Hello and welcome to the Premier League early kick-off at St Mary's! Relegation fighters Southampton host fifth-placed Chelsea today, in a must-win game for both sides. Chelsea need to keep the pace with the top four, while Southampton need a win to drag them out of the bottom three (for a few hours at least).