The Spain international, who missed Saturday's La Liga defeat at Real Madrid, trained with the rest of the squad on Friday, Barca said in a statement on their website.
Assistant coach Jordi Roura, who is standing in for Tito Vilanova while he undergoes cancer treatment in New York, said a late decision would be made about whether Xavi would be included in the squad for Saturday's La Liga game at home to bottom side Deportivo La Coruna.
"He completed a full session with his team-mates," Roura told a news conference on Friday.
"We'll see tomorrow after training how he feels and whether we include him in the list," he added.
"We will then see how things develop over the next few days to see whether he can play against Milan."
Barca need to overturn a 2-0 deficit to Milan in their last-16 second leg at the Nou Camp if they are to keep alive their hopes of a third European crown in five years.
Victory against Depor, meanwhile, would put them 14 points clear of second-placed Atletico Madrid, who are at home to Real Sociedad on Sunday.
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