MADRID (Reuters) -- Barcelona midfielder Ibrahim Afellay has torn a muscle in his left thigh and will be out of action for up to five weeks, the European champions said on Sunday.

The Dutch international picked up the injury in Barca's 2-1 friendly defeat to Manchester United in Washington DC on Saturday, but will stay with the team as they continue their pre-season tour of the United States.

Afellay will miss the La Liga curtain-raiser against Real Madrid when the league champions take on King's Cup winners in the Spanish Super Cup on Aug 14 and 17.

The 2011-12 La Liga season kicks off on the weekend Aug 20-21.

SI Apps
We've Got Apps Too
Get expert analysis, unrivaled access, and the award-winning storytelling only SI can provide - from Peter King, Tom Verducci, Lee Jenkins, Seth Davis, and more - delivered straight to you, along with up-to-the-minute news and live scores.