Karachi: Pakistan pacer Umar Gul's participation in the three-match Test series against Australia is doubtful because of a knee injury. 

The initial MRI reports have suggested that Gul might need several weeks to recover from the knee injury, sources said.

The Pakistan Cricket Board (PCB) has decided to rush fast bowler Mohammad Sami to Australia ahead of the first Test beginning at the Melbourne Cricket Ground from December 26. Sami will fly for Melbourne Wednesday night.

According to sources, Gul picked up the injury during the tour of New Zealand that concluded earlier this month. A hero of Pakistan's successful World Twenty20 campaign in England last summer, Gul is part of a four-man pace attack which Pakistan selected for the twin tours of Australia and New Zealand. Sami will be the fifth pacer in the Pakistan squad.

However, it is likely that Gul might return home and start a race against time to get fit for the five-match One-day series against Australia which will begin in Brisbane from January 22.

Gul's injury could tempt Pakistan to field two spinners in the Boxing Day Test. Leg-spinner Danish Kaneria is almost certain to be in the playing eleven for the opening Test after doing well in New Zealand while off-spinner Saeed Ajmal, who has been impressive during the three-day tour match against Tasmania in Hobart earlier this week, is also in contention.