Bayern Munich and Germany midfielder Sebastian Deisler is ruled out of the World Cup this summer with a knee injury, the German Football Association (DFB) confirmed on Saturday. Deisler needs to undergo a surgery in his right knee and will be sidelined for about six months, the DFB said on their official website. The 26-year-old Deisler has sustained the injury last week after colliding with Bayern team mate Owen Hargreaves during the training. Deisler's career has been hit by a string of severe injuries, undergoing four operations in his bad right knee and missing a bunch of major events with the 2002 World Cup at the top of the list.