
Lewandowski, who is the club’s top scorer this season with 25 goals in all competitions, played 90 minutes in the La Liga leaders’ 1-0 loss at Almeria yesterday as well as their Europa League playoff loss to Manchester United last week.
Barcelona did not give a potential return date for the 34-year-old striker.
The club plays Real in the first leg of the Copa del Rey semifinals on Thursday.
“Robert Lewandowski has strained the biceps femoris in his left hamstring. The Polish striker is unavailable until the problem clears up,” Barcelona said in a statement.
“He is out and his recovery will determine his availability.”