“He’s had a bit of soreness, so there’s a big question-mark for Christian.
“Kai Havertz is back in training and can join us in Southampton.”
Despite Pulisic being out of favour recently, Tuchel believes he’s still got a lot to offer the side.
He said: “He proved in many weeks that he has the level to be a Chelsea regular player, to have a big impact in this club.
“It’s a challenge now to hold this level, to improve and to maintain the level and keep improving.”