Chelsea v Southampton player ratings: Joao Felix 5, Fernandez 6; Ward-Prowse 9, Lavia 8

CHELSEA RATINGS: Kepa Arrizabalaga - 6 Started well by making a good save but ended the half by conceding a goal from a free-kick. Got called into action just once in the second half and made a good save. Reuters

Cesar Azpilicueta - 6 Was having a solid game on the right wing until he needlessly tripped Perraud to concede the free-kick that led to the goal. Got more involved in attack as the second half wore on and had some chances. Had to leave the field with what looked like a serious head injury. AP

Ben Chilwell - 6 Looked like an upgrade on Cucurella. He got forward well and was assured on the ball. He also combined well with Fofana in front of him. EPA

Benoit Badiashile - 5 Had a shaky first half and guilty of not being aware of his surroundings a number of times. He also didn't look like the confident, self-assured player he has proven to be since he joined the Blues. Played better after Fofana was introduced. AP

Kalidou Koulibaly - 6 Looked the more assured of the Blues’ centrebacks. He defended well, looked comfortable in possession, and cleared a ball off the line early in the game. Reuters

Mateo Kovacic - 7 A busy day in the middle for the Croatian midfielder. Helped out in defence by making last-ditch tackles and clearing the lines. AFP

Enzo Fernandez - 6 Worked hard and kept things simple in the middle. The presence of Kovacic in midfield gave him more freedom to move forward. EPA

Noni Madueke - 5 Was bright from the start. Denied by an impressive save from Bazunu in the 13th minute. His trickery caused problems for the Saints backline, but he lacked the final pass to create openings for his teammates. EPA

Joao Felix - 5 Starting in the No 9 position, was less involved in build-up play and he cut a frustrated figure. EPA

Mason Mount - 5 Another game where Mount worked his socks off but proved to be ineffective going forward. Has to do better if he is to claim a spot in the first XI. PA

David Fofana - 6 It was a surprise to see him hooked at half-time as he was a thorn in the Saints defence. Positioned on the right side of the attack, held up the ball well and ran at opposition defenders with pace. AFP

SUBS: Raheem Sterling (David Fofana, 46) - 6 Lively and should have scored twice but was denied by goal-line clearances. He seemed to enjoy playing on the right side of the attack. AP

Wesley Fofana (Koulibaly, 46) - 7 Calmly went about his business as he snuffed out attacks and made last-ditch tackles. Getty

Kai Havertz (Mason Mount, 64) - 6 Should have shot instead of playing a pass to Sterling in the 68th minute. Created another good chance via a cross, which was cleared off the line in the 70th minute. Reuters

Mykhailo Mudryk (Madueke, 64) - 5 Didn't provide the kind of positive impact Graham Potter would have expected. Struggled against Maitland-Niles and seemed devoid of ideas when he got on the ball. Getty

Trevor Chalobah (Azpilicueta, 84) - N/A Brought on to help stop counterattacks as the Blues chased the game. Conor Gallagher (Ben Chilwell, 84) - N/A. Getty

SOUTHAMPTON RATINGS: Gavin Bazunu - 9 Man-of-the-match display to deny the Blues. He was a commanding presence and helped relieve pressure by repeatedly coming out to claim crosses. EPA

Romain Perraud - 8 Almost cost his team a goal when he got outmuscled by Madueke. More than made up for it in the second half by clearing a Sterling shot off the line. Kept up his impressive second-half performance by making several last-ditch tackles. PA

Ainsley Maitland-Niles - 8 The loanee from Arsenal had heart-in-mouth moment early in the second half when he was shrugged off the ball by Sterling to create an opening. Made amends by clearing a goal-bound shot from Sterling in the 68th minute. AP

Jan Bednarek - 8 The decision to recall Bednarek from his loan spell early looked better every minute at Stamford Bridge. The tall centre-back was rock-solid in defence and displayed excellent leadership. He was strong in the air against Chelsea’s short forward line. Getty

Armel Bella-Kotchap - 8 The 23-year-old looked like a veteran against a star-studded Chelsea frontline. The German youngster kept things simple and never seemed fazed by the late flurry of attacks. AFP

James Ward-Prowse - 9 Another day, another Ward-Prowse free-kick. His goal crowned what had been an impressive first-half performance from the Saints. Worked hard in the second half as the Blues piled on the pressure. AFP

Romeo Lavia - 8 An energetic and explosive performance in the middle of the pitch. He wasn't afraid to go for 50/50 balls and won many of his duels. Celebrated like he had scored when he denied Sterling a second shot at an open goal in the second half. AP

Mohamed Elyounoussi - 6 The winger worked hard on the left but was ineffective going forward. Struggled one v one against the experienced Azpilicueta and didn't put in enough balls for Onuachu. AFP

Kamal-Deen Sulemana - 6 Put pressure on Badiashile to create an early chance which got cleared off the line. Showed his trickery a number of times but lacked that extra bit of quality to take advantage of the good positions he found himself in. PA

Stuart Armstrong - 6 Had a quiet first half until he was fouled for the Saints opener. Improved after half-time and kept things simple until he was replaced. Getty

Paul Onuachu - 7 A menace to the Blues backline. The lanky striker constantly won aerial duels which helped bring his teammates into play. He also showed his nice range of touches with his feet and looked like a genuine threat up front. AFP

SUBS: Theo Walcott (Stuard Armstrong, 59) - 6 Used his pace well to beat Chilwell and create a chance for Armstrong in the 73rd minute. PA

Adam Armstrong (Kamal-Deen Sulemana, 59) - 6 Could have done better when he was denied from point-blank range by Kepa in the 70th minute. AFP

Sekou Mara (Onuachu, 59) - 5 Should have put the game to bed when he was played through on goal in the 96th minute. Getty

Carlos Alcarez (Elyounoussi, 87) - N/A Too late to make an impact. Lyanco (Niles, 90) - N/A. Getty

Chelsea’s season sunk to a new low after the London club lost at home to last-placed Southampton in the Premier League on Saturday in a game that also saw Cesar Azpilicueta carried off on a stretcher with a head injury.

James Ward-Prowse scored from a free kick on the stroke of half time to ensure Graham Potter’s team went a fourth consecutive match without a win in the league.

Five of Chelsea’s eight January signings were in the starting lineup and Potter saw them struggle to find any invention against a Saints side set up by interim boss Ruben Selles to frustrate the host's expensive ensemble.

Chelsea have scored just once at home in 2023, and the lack of a recognised striker was apparent yet again.

Southampton took the lead in a familiar fashion. Ward-Prowse’s free kick was the 17th he has scored from in the Premier League, putting him one behind David Beckham on the all-time list. This one arced over Chelsea’s wall and dropped crisply into the bottom corner beyond Kepa Arrizabalaga’s despairing dive.

Chelsea tried to respond after the break, but even the introduction of Kai Havertz and Mykhailo Mudryk failed to produce results while Chelsea was camped in Southampton’s defensive half for the final 30 minutes.

There was a 10-minute stoppage in play after Azpilicueta needed lengthy treatment after being hit in the head by an attempted overhead kick by Sékou Mara in the 74th minute.

Azpilicueta was taken off on a stretcher wearing a neck brace and breathing from an oxygen mask.