New Delhi: Sourav Ganguly, the former India captain, has sounded a warning ahead of the Australia tour by suggesting that Zaheer Khan has not done enough to prove his fitness for the first Test against Australia starting on the Boxing Day. Zaheer injured his right hamstring on the first day of the Lord's Test during the tour of England in July. Though he recovered from that injury, a recurring ankle injury re-surfaced during the practice match against Northampton ahead of the third Test at Edgbaston, forcing Zaheer to abort the series that India eventually lost 4-0. He underwent ankle surgery and started his rehabilitation at the National Cricket Academy in Bangalore, before participating in Mumbai's Ranji Trophy match against Orissa in Cuttack. Zaheer bowled 22 overs in the match - which Mumbai won by an innings and 210 runs - and picked up four wickets in his first competitive outing. Ganguly, 39, felt India's pace spearhead could not be judged on the basis of one domestic outing. "I feel Zaheer is still not hundred percent fit and we can't afford to have a 50 percent fit Zaheer in Australia. For India, Zaheer still needs to play a lot more matches and for that he needs to be fully fit. One Ranji Trophy game is not enough," he said at the launch of Wisden India here on Friday. "Still there are 24 days left and I believe he will play another Ranji game as well as two practice matches in Australia. The BCCI has planned his schedule well, unlike 10 years back when I had to appear for a fitness test only 10 days prior to an important tour."Ganguly also commented on R Ashwin's recent success - he was Man of the Series in the Tests against West Indies with 22 wickets in his debut series - by saying the offspinner would encounter entirely different conditions in Australia. "Ashwin is a gifted cricketer. But bowling in India with SG Test balls against an inconsistent West Indies batting line-up is completely different from bowling with Kookaburra balls," said Ganguly. "Also the quality of batsmanship will certainly be higher."Praveen Kumar's injury has left one spot open in the Test squad, and the name doing the rounds is Irfan Pathan, who has taken 21 wickets at an average of 14.14 in four Ranji matches. Ganguly did not choose to comment on who the best replacement for Praveen was, but felt youth was the way to go. "We should have a good young pacer, whoever it is. As far as Irfan is concerned, I have heard that he is bowling well but my question would be whether he is good enough to get into the team on his bowling alone,â he said. India play four Tests on their tour of Australia.