Australia's miserable tour of India could become even worse with the captain Michael Clarke battling a back injury that may affect his batting on the final day in Mohali. Clarke has had ongoing problems with his back for many years and after hurting it during the warm-up on the fourth morning, he went on and off the field a number of times during India's batting, leaving Brad Haddin in charge during his absence.Clarke was unable to take his new No. 3 position when Australia batted later in the afternoon and he also did not come out at No. 4 or No. 5, with Phillip Hughes, Steven Smith and the nightwatchman Nathan Lyon all sent in ahead of him. Given that he is Australia's leading run scorer during the series it was a major blow as they aimed to stave off defeat."Michael injured his back in the warm-up this morning," the team physio Alex Kountouris said. "He'll undergo further treatment overnight. We'll assess that and see how it settles in the morning."Clarke's forced move back down the order allowed Hughes to shift back up to first drop and he made his innings count, reaching 53 not out at stumps, easily his best score of what has otherwise been a horror tour for him. The fast bowler Peter Siddle said he was confident Clarke would bat on the final day but he conceded the captain had been really struggling on Sunday."I think he'll definitely bat," Siddle said. "It was very sore throughout the day. Everyone knows he's had a bit of trouble with his back. He got some treatment after we came off the field and everything seems to be going along fine. Knowing Michael he'll do everything he can tonight with Alex and be ready to go tomorrow morning as soon as possible, no doubt. He'll want to get out there first-up. I think he'll be ready to go."You never want to see your mate in pain or hurting or going off the field and getting treatment, but the boys stuck at it well. Hadds took control out there when he was off the field and did a good job and the boys kept going about their business. I don't think anyone worries about it too much, but it was nice for Hughesy to get out there and dig in and batted superbly today."Clarke's back has caused him problems for many years but he has never missed a Test due to the pain. However, Australia have only three days off ahead of the fourth and final Test in Delhi, a short turnaround for Clarke and Australia's medical staff to ensure his fitness.