Chelsea lost in the second home game in a row without scoring again - this happened to the team for the first time in the 21st century. In the first half, Michael Obafemi took Southampton ahead, and in the second Nathan Redmond strengthened the advantage of the guests.
Chelsea's lead over Tottenham’s fifth came down to three points.
Chelsea - Southampton 0: 2.
Goals: Obafemi, 31, Redmond, 73.
Chelsea: Kepa - Rudiger, Zuma (Mount 46), Tomori - Aspilicueta, Kante, Jorginho, Emerson - Hudson-Odoi (Pulisic, 67), Abraham, Willian (Pedro, 84).
Southampton: McCarthy - Cedric, Stevens, Bednarek, Bertrand - Armstrong (Romeu, 84), Ward Praus, Heubjerg, Redmond - Obafemi (Ings, 69), Adams (Bufal, 80).
Warnings: Jorginho, Tomori, Cante - Bertrand, Bufal.