Clarke, Ponting invalided out of practice match

Shane Watson is a back spasm away from the Australian captaincy. This truth was underlined in Brisbane on the final day of the national team's training camp, when Michael Clarke was forced to retire hurt following a recurrence of a chronic back problem while batting in a practice match against a Queensland XI.

Watson led the Australians in the afternoon as Clarke reclined at the boundary's edge, accompanied in repose by Ricky Ponting, who missed the fixture due to calf soreness. While neither are in any doubt for their Test and ODI tasks on the tour of Sri Lanka in August, their ailments provided a reminder that Clarke will face back problems for the remainder of his career, while at 36 Ponting is no longer a young man.

Tim Nielsen, Australia's coach, said Clarke and Ponting were being cautiously managed.

"[Clarke] pulled up a little stiff which is why he retired and we're just going to take the opportunity to get everybody out there," Nielsen told AAP. "[Ponting] has had a bit of a sore calf as well which we're just being careful about. Really it's a training day for us and, if these guys were like this at training, we wouldn't expect them to train so we certainly won't put them through the fielding."

Clarke has faced intermittent back problems through his career, most recently struggling during the final Sheffield Shield match before the first Ashes Test last year, in which he appeared restricted, though he denied it had been a problem. As for Watson, Nielsen said he was ready and able to assume the top job whenever Clarke was not feeling capable of fulfilling his duties.

"Very much so. Selectors don't just give people the vice-captaincy with the thought you deserve it because you played well," Nielsen said. "It's an idea that if something does happen to the captain, who is the person we feel can take over the reins and do a good job?

"We can't forget that we have people with the experience of [Brad] Haddin and Ponting still around the team and, I'm sure if Shane needs to, he will lean on them pretty strongly, and also Michael Hussey. While he's the nominated one and probably giving him the opportunity is a longer-term view, he certainly won't be on his own out there if he captains the side.

"Most importantly he understands that he's there as a support structure there for Michael. He does take on a bit more respect naturally just through the fact he's a nominated leader now rather than being a senior player, but he's always been one of those guys who is willing to put his point of view across to the team and work hard with the group. In the last 12 to 18 months he's certainly taken on more and more respect in that area."

Australia's batsmen fared well enough at Allan Border Field, with David Hussey (76) and his brother Michael (46) among the runs, along with Shaun Marsh (47). However, the Sri Lankan slow bowlers will warm to the sight of young Queensland spinner Jason Floros returning the figures of 4 for 25 against batsmen soon to be playing at venues including Kandy, Colombo and Galle.