Callum Hudson-Odoi starts his first Premier League game of the season.
That is the one change from the win at Lille midweek in the Champions League and with Reece James the player replaced, it appears Frank Lampard is switching back to a four-man defence.
That will have new England call-up Fikayo Tomori and Kurt Zouma at its heart. Cesar Azpilicueta is back at right-back and on the left, Marcos Alonso makes his 100th appearance in the Premier League for Chelsea.
Southampton make two changes from their defeat at Tottenham last week. Yan Valery is in for Jannik Vestergaard and Shane Long replaces Sofiane Boufal.
Chelsea Kepa; Azpilicueta (c), Zouma, Tomori, Alonso, Kante, Jorginho, Mount, Willian, Abraham, Hudson-Odoi.
Substitutes Caballero, Christensen, James, Kovacic, Barkley, Pulisic, Batshuayi.
Southampton Gunn; Valery, Bednarek, Yoshida, Bertrand, Hojbjerg (c), Romeu, Ward-Prowse, Redmond, Long, Ings.
Substitutes: McCarthy, Stephens, Danso, Armstrong, Boufal, Adams, Obafemi.
The referee is Paul Tierney
Chelsea have won more Premier League games (eight) and scored more goals (22) than any other side against Southampton in the Premier League at St Mary’s.In the Premier League we have won eight, drawn two and lost just one of our 11 meetings at St Mary’s. Chelsea also won 5-1 there in the third round of the FA Cup in 2013.Our one defeat in that time was in March 2013 when Jay Rodriguez and Rickie Lambert secured the points for the Saints. John Terry had equalised for the Blues.Chelsea have scored at least one goal in each of our past 15 away games against Southampton in all competitions, last failing to find the net in December 1997.
Frank Lampard’s last Premier League goal as a player came against Southampton in May 2015 while playing for Manchester City. Lampard scored eight goals in 19 Premier League games against the Saints.Southampton are seeking a first home win in the Premier League since 13 April. They have lost two (Liverpool and Bournemouth) and drawn three (Bournemouth, Huddersfield and Man Utd) since then.
Five of Southampton striker Danny Ings’ last six Premier League goals have come against ‘big-six’ opposition, including both of his strikes this season - against Tottenham and Liverpool.