Torres started for a third successive game but lasted just 11 minutes before being substituted after failing to shake off a blow to his left knee.
Chelsea recovered to make amends for the defeat to Basle in the first round of Champions League fixtures and last season's Europa League loss at the home of the Romanian champions.
"The doctor is very confident it's not a big injury," said Jose Mourinho, the manager. "It's something in his knee, his ligament, and we have to wait for the scan tomorrow."
Should the scan reveal significant damage, Torres could miss the first game of a double-header with Schalke which could determine the group winner.
In a far cry from their display in the same stadium in March, 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.
Midfielder Juan Mata, who has been overlooked by Mourinho on the domestc front, impressed after starting the game and pledged to continue to improve as he attempts to win back a regular first-team place.
"I have just kept going," he said. "I have trained well and been getting ready for every game. That's it. Today I really enjoyed playing - it is important for us to play with the ball. I was happy with the way I played."
Asked what he had improved since being sidelined, he added: "I don't know. I have felt the same. I just try to improve every season."