Chelsea made amends for a 1-0 defeat in their last home match against Leicester City with consecutive away wins in the Premier League, leaving them in fourth place going into their tie with Southampton.
A 2-1 win at Watford was followed by a 1-0 win at Crystal Palace to see Chelsea earn a five-point cushion over fifth placed Arsenal, as the sides battle to finish in the top four for Champions League football.
Meanwhile, Ralph Hasenhüttl has improved Southampton's performances but has suffered back-to-back defeats after taking over earlier in the month. The Saints could slip back into the relegation zone with a poor result on Wednesday.
Olivier Giroud was the latest casualty for Chelsea as the Blues' injury list grows. The France international was seen limping away from Selhurst Park on crutches after going down under a challenge from James Tomkins in the recent win.
Maurizio Sarri has said Cesc Fabregas' absence from the match day squad on Sunday was down to a 'neck injury', while forgotten midfielder Danny Drinkwater has also gone onto the treatment table.
Pedro will also be out for the match after suffering a hamstring injury against Watford. Sarri will hope for positive news on the fitness of Callum Hudson-Odoi and Ruben Loftus-Cheek, amid a busy period of fixtures and with several attacking players out.
Pierre-Emile Hojbjerg has apologised after a wild lunge against Fernandinho in the defeat to Manchester City. It will see him suspended for the upcoming Chelsea match. Chelsea have no suspensions to contend with.
Chelsea Potential Starting Line-Up
The absence of Olivier Giroud and Pedro may see Eden Hazard continue in a wide position after a number of weeks operating as a false-nine for Chelsea. In four matches in the central position, Hazard has contributed three goals and three assists for Chelsea, but he returned to the left-wing against Palace on Sunday.
Alvaro Morata made his first league appearance for almost a month against Palace after Giroud was taken off injured. He could start against Southampton as rumours are rife of him leaving the club in January.
Sarri could make further rotations after a busy fixture period, but he has so far kept those changes to a minimum in his time as Chelsea boss; Kepa Arrizabalaga, Cesar Azpilicueta, Antonio Rudiger, Marcos Alonso and N'Golo Kante have started every league match still this season.
Mateo Kovacic was rested against Palace, with Ross Barkley coming in, but the Croatian will likely be recalled to the line up.
Southampton Team News
Ryan Bertrand is a doubt for the trip to his former club after suffering a minor back injury. Cedric Soares is also a doubt after missing the Man City game with a calf complaint.
Michael Obafemi is another potential absentee as he recovers from a knock.
TV channel & kick-off time
The match at Stamford Bridge and kicks off at 7:45pm GMT (14:45pm ET) on Wednesday and it will be shown on Sky Sports in the UK.
Best Opta Match Facts
Chelsea have won each of their last seven games against Southampton in all competitions, scoring two or more goals in six of those.
Chelsea haven’t lost consecutive home Premier League matches since November 2011, when they lost to Arsenal and Liverpool.
Southampton have lost nine of their last 11 Premier League matches in London (W2).
Since keeping back-to-back clean sheets in October, Southampton have conceded at least once in their last 10 Premier League games – the longest current run in the competition.
Eden Hazard has had a hand in seven goals in his last six matches against Southampton for Chelsea in all competitions, scoring four and assisting three.