After facing serious injury problems in the last few weeks with up to seven players out, Xavi got good news on Friday as Lewandowski, Frenkie de Jong, Jules Kounde, Raphinha and Pedri participated in Barcelona training before the big game.
Defender Joules Kounde and midfielders Pedri and Sergi Roberto have been ruled out, but Lewandowski, De Jong and Raphinha are ahead of schedule in their recoveries and all signs point to last year's LaLiga top scorer being fit to start against Real.
"I can't reveal the line-up right now, but (Lewandowski) is fine and I'll make my decision tomorrow," Xavi told a press conference.
"It's complicated (to take risks with injured players) and in the end, only those who are 100% will play tomorrow."
Xavi, who had to call up eight academy players for the Champions League match against Shakhtar Donetsk on Wednesday, praised the club's young talent for delivering at the highest level.
Barca secured a hard-fought 2-1 win against Shakhtar thanks to a brilliant display by 20-year-old Fermin Lopez, who is becoming a regular in the first team alongside teenagers Lamine Yamal and Marc Guiu.
"The homegrown players give us something extra. They work hard, they know the importance of tomorrow's game and what it means for our people," Xavi said.
"There are more nerves, more emotions, but you have to control them. You have to be smart but it's hard because the heart pumps faster and the blood boils."
Real lead the LaLiga standings, level with Girona, the surprise packages of the season, on 25 points from 10 games. Barcelona are third on 24 points, two ahead of Atletico Madrid, who have a game in hand.
