Pulisic suffered a hamstring injury during Chelsea's shock 5-2 home defeat against West Bromwich Albion in the Premier League on Saturday and had been a doubt for the match against the Portuguese side, which will be played in Spain due to COVID restrictions, on Wednesday.
The United States captain appeared to pick up a knock that forced him to come off at half-time. Pulisic initially entered the pitch alongside his teammates for the start of the second half, only to turn around and speak to his manager before coming off.
"They are fit enough to be in the squad and to go be in the squad all three. So this is good news," Chelsea boss Thomas Tuchel said in a news conference on Tuesday.
"Christian went out right before the accident, like before an injury could happen. So, he said it in half-time he feels like if he continues it will be an injury coming so we need to take him off. And Tammy is in the squad and [Ngolo] just did the last test and will be on the bench. He feels comfortable enough to be on the bench."