Michael Clarke has never missed a Test match due to his ongoing back injury but faces an enormous challenge to prove his fitness over the next three days after struggling through the Mohali Test. Clarke has not given up hope of playing the fourth and final Test, which starts in Delhi on Friday, but when asked if he was confident of leading the side his uncertain facial expression and pause before answering betrayed a serious concern.

"My fingers are crossed I will be doing everything I can to give myself the best chance," Clarke said. "I guess I am always pretty positive, touch wood I haven't missed a Test match due to injury so far in my career and I wouldn't like this to be my first one. If I can't perform at my best, if I feel I am going to let the team down, I won't be taking the field."

Clarke was visibly hampered during his 52-minute innings on the final day in Mohali and batted at No.6 after being in too much pain to bat on the fourth afternoon. He had been on and off the field several times during India's innings on Sunday and left Brad Haddin in charge, but the vice-captain Shane Watson, who is rejoining the squad after flying home for the birth of his child, would be the likely leader in Delhi if Clarke is ruled out.

That would be a fascinating turn of events after Watson was one of four players left out of the Mohali Test due to their failure to complete a task set by the coach Mickey Arthur. Watson subsequently flew home for the birth of his first child but on the way said he thought the punishment was "very harsh" and that he would use his time at home to weigh up his cricket future.

"It's very positive that Watto is coming back," Clarke said. "I know all the boys are looking forward to having him back and no doubt if I am unavailable ... I haven't spoken to the selectors but I would imagine that Watto would be captain that's for sure."

Watson was in line for the captaincy for last year's Boxing Day Test against Sri Lanka on another occasion when Clarke had an injury concern - on that occasion a hamstring problem - but Clarke was passed fit. Clarke's back complaint has affected him for his entire career, and he said although it was painful he and the team physio Alex Kountouris were well versed with how to manage the problem when it flares up.

"It's pretty sore," Clarke said. "Fortunately I have got a few days before the next Test and I will spend as much time with Alex as I can to get it right. It is the same problem I have had since I was 17 and I have been trying to manage it throughout my career and the next four days will be no different to normal when my back goes on me like this. It's about plenty of treatment, listening to the expert and doing everything I can to get it right for the next Test match."

Clarke was in the field for all of India's second innings on the final day in Mohali, where he tried to rally his men to defend the small target of 133, but India's batsmen reached the target with 15 balls to spare. The loss left Australia 3-0 down in a series for the first time in nearly 25 years and Clarke will be doing everything in his power to avoid becoming the first captain since Bill Lawry in South Africa in 1969-70 to lead Australia on the wrong end of a 4-0 whitewash.

Brydon Coverdale is an assistant editor at ESPNcricinfo. He tweets here