Chelsea boss Thomas Tuchel has revealed that he was forced to make a half-time change against West Brom after Christian Pulisic felt he could not continue.
Mason Mount was sent on in Pulisic’s place for the second half of the match after the American once again complained of hamstring trouble.
Pulisic felt discomfort after running on to the pitch and it was therefore decided that he would be taken off.
He has been plagued by injury problems since joining the Blues and now appears to be a doubt for Wednesday’s Champions League game against Porto.
Boss Tuchel told the club website: “Christian did a sprint when he came back out for the second half and said that he felt his hamstring would not survive the game if he continued.
“So we had to make the decision to substitute him straight away.”
It remains to be seen whether Pulisic and N’Golo Kante will be fit enough to take part in Wednesday’s quarter-final first leg.
Tuchel is expected to give an update on their condition at a press conference on Tuesday.
Kante missed the 5-2 defeat against West Brom after picking up a hamstring injury while on international duty with France last week.