Pakistan suffered a big setback ahead of the ICC Champions Trophy when one of their main strike bowlers Shabbir Ahmed was ruled out of the tournament due to a knee injury.

Pakistan's request to replace Ahmed with all rounder Azhar Mahmood has been approved by the Event Technical Committee of the ICC Champions Trophy, beginning in England on September 10.

Ahmed has been diagnosed with a cartilage tear, a Pakistan Cricket Board press release revealed.

According to doctors, it would take at least six weeks for Ahmed to recover from his knee injury.

Azhar Mahmood is already in England, playing county cricket with Surrey.

Ahmed is the second Pakistani bowler to have been sidelined due to injury. Earlier, speedster Umar Gul was declared unfit to play for one year following a surgery.