The Spain international is targeting an historic comeback as the Catalans look to overturn a 2-0 defeat from the first leg
The Blaugrana were stunned by a 2-0 defeat in the first leg at San Siro, but Xavi remains optimistic that Barcelona can reach the quarter-finals.
"I am quite optimistic that we can turn the first-leg defeat around, even though Milan are a strong and competitive team. The pitch will be in great condition and the fans will be behind us," Xavi told El Mundo Deportivo.
"Everybody has responded well to our recent losses and that encourages the team. We want to give the fans something to cheer about and will attack in numbers right from the start.
"We will try and get a goal in the opening 15 or 20 minutes to get back into the tie. We have 90 minutes to turn things around, and perhaps even 120 minutes. Anything can happen in the game.
"We have to act careful. We cannot afford to give away free-kicks in dangerous positions or lose possession easily. We have to find back the fluidity that has seemingly been missing recently."
Xavi is currently recovering from a hamstring problem, and could make his comeback against Milan on Tuesday.