Manager Arne Slot rotated freely in the squad and replaced the entire starting eleven compared to the derby against Everton last weekend.
Among other things, the youngsters Giovanni Leoni, 18, Trey Nyoni, 18, and Rio Ngumoha, 17 years, got a place in the team.
For Isak, who missed the preseason matches due to the infected transition, the league cup match is an excellent opportunity to get match fit.
Southampton was extremely close to taking the lead just before Isak got the service. Stuart Armstrong hit the post whereupon Léo Scienza headed the rebound wide.
The match is ongoing.
