Che Adams came off the bench to score in the 68th and 84th minutes — the second coming from a spectacular scissor kick — to earn Southampton a first win at the third time of trying.
Leicester, which went ahead through James Maddison’s 54th-minute free kick, is still without a victory despite having taken the lead in both its home games. From 2-0 up, Brendan Rodgers’ team drew 2-2 with Brentford in the opening round before losing 4-2 at Arsenal last weekend.
Rodgers chose to leave Fofana out of the matchday squad, with the center back linked with a big-money move to Chelsea. Meanwhile, midfielder Youri Tielemans only started on the bench — and came on in the 65th — amid uncertainty over his future.
Jamie Vardy started for Leicester after signing a new deal keeping him at the club until 2024.