Lewandowski suffered concussion and broke his nose and cheekbone in Bayern's DFB-Pokal semi-final penalty shoot-out defeat to Borussia Dortmund following a collision with goalkeeper Mitch Langerak.
Despite this, team-mate Jerome Boateng has revealed the Poland international could feature at the Camp Nou.
"He moved well and made a good impression, it looks like he's fit to play," Boateng said.
"He didn't have any fear, he is very brave and he will get used to the mask."
The 26-year-old Lewandowski, the German champions' top-scorer with 23 goals, sat out Bayern's 2-0 league defeat at Bayer Leverkusen on Saturday to try and get him fit for the first leg in Spain.
Bayern have said they will leave the decision to Lewandowski as to whether he plays.
And the 26-year-old posted a picture of himself wearing the mask on Sunday with the text "Ready for the next challenge".
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