The midfielder was withdrawn early in the second half of Barca's quarter-final first leg victory at the Parc des Princes on Wednesday.
He was later confirmed to have suffered heavy bruising to his pelvic region, with coach Luis Enrique revealing the 30-year-old is all but certain to miss the weekend's action at Camp Nou.
"He's much better, he didn't train today so in principle, unless there's a miracle, he won't be in the squad," the Barca boss explained. "He won't be playing tomorrow."
With Barca still in the running for La Liga, Copa del Rey and UEFA Champions League honours, Luis Enrique also discussed the hectic schedule his side are facing.
"I don't want it to sound like I'm making excuses," he added.
"Fitness wise it certainly conditions you to have less time to recovery. That's obvious. You can see that in the way we train. We don't want to overload the players.
"It couldn't get much tighter, the schedule, but other teams at our level have to deal with the same kind of arrangements.
"It makes things difficult - I'm exhausted and I haven't played a minute so imagine what it's like for the players.
"We're coming to the end of the season, in the position we want, with three trophies available and that's a huge stimulation for us."
