The Argentine World Player of the Year strained a hamstring in last week's 2-2 first-leg draw in Paris but trained normally on Tuesday and it looks likely he will be available.
The build-up to the clash at the Nou Camp has been dominated by Messi's injury but Ancelotti appeared uninterested at his pre-match news conference.
"It's not our problem," he said.
"Our strategy will be the same with Messi or without Messi," added the Italian, one of only six men to have won the European Cup as a player and a coach.
"The key is to have confidence and personality in a very difficult stadium against a team that is probably the best in the world.
"We have to think about what we did well in the first match and try to repeat that tomorrow."
Ancelotti was quizzed about criticism of David Beckham for his performance in last week's first leg and whether the former England international would start on Wednesday.
"Some criticised [Beckham] and some were happy," Ancelotti said.
"I was happy so Beckham should be happy. When the manager is happy I think he has a lot of possibility to play."
Ancelotti dismissed a suggestion that as a former player for Barca's bitter rivals Real Madrid Beckham may be given a hostile reception by the home fans on Wednesday.
"Beckham has a very good image, he doesn't have a problem to play here," he said. "He is an international player and I think everyone respects him."
