Just a few hours after learning Torres would face no further Football Association disciplinary action following his altercation with Tottenham defender Jan Vertonghen, the striker hobbled off at the National Arena.
Blues boss Jose Mourinho confirmed Torres will not be available to link up with Spain following Sunday's match at Norwich, for which he is suspended following his dismissal at White Hart Lane, with a scan required to determine the full extent of the problem.
"It's something in his knee, his ligament, and we have to wait for the scan," Mourinho said.
"The doctor is very confident it's not a big injury, like we had with Marco van Ginkel (who is out for six months).
"He knows that he doesn't play against Norwich. He knows that he cannot go to the national team.
"He knows he has 15 days until the next match he can play, which is against Cardiff.
"Let's see the scan. If the injury is an injury for 15 days, I think he'll be fine. That's okay.
"The problem is if it's more time and it's a pity for the guy, because he's in a very good moment."
Chelsea recovered from the loss of Torres to make amends for the round one loss to Basle and last season's Europa League defeat at the home of the Romanian champions with a comprehensive triumph.
Ramires scored either side of a Daniel Georgievski own goal before Frank Lampard added a late fourth for the 2012 European Cup winners and 2013 Europa League champions.
Mourinho is eager to avoid the second-tier European competition and is confident ahead of successive matches with group leaders Schalke.
"We have to do everything we can to keep Chelsea playing in the Champions League, because the Champions League is our competition," he added.
"At this moment I don't want to think about being first, I want to think about qualifying. After that we'll see, but I think everything is open."
Mourinho praised the contributions of Andre Schurrle and Juan Mata, who has been a peripheral figure so far this term due to Mourinho's desire for him to track back more.
"He played very good with the ball, as he always does," Mourinho added.
"And he played very good without the ball, as he never did."