Australia's chairman of selectors John Inverarity says captain Michael Clarke has a 50-50 chance of playing in the second test against Sri Lanka which starts at the Melbourne Cricket Ground on Boxing Day.
Inverarity said Australia would take no risks with Clarke, the world's No.1-ranked batsman, who was forced to retire hurt with a hamstring injury during the second innings on the first test in Hobart last week.
Clarke was limited to light duties when the team trained at the MCG on Sunday. Inverarity watched the session and said no risk would be taken with Clarke who made scores of 74 and 57 retired in Australia's 137-run first test win.
"He's a very precious asset and I would go low risk," he said. "He's very upbeat. He desperately wants to play."
If Clarke is forced to miss the Boxing Day test, the traditional highlight of the Australian summer, Shane Watson will assume the captaincy and batsman Usman Khawaja will join the Australian lineup.
Watson has never captained Australia in a test but said he was ready for that challenge.
"It's just about as big as it gets for an Australian cricketer," Watson said. "It's an amazing opportunity to think that something like that has come along in your life.
"But I'm trying not to get too far in front of myself at the moment. I know Michael will be doing everything he can to get right for this test match."
Watson said as captain he would rely on gut instinct to make the right calls for the Australian team.
"Until you actually captain a side you don't really realize the intuition you've developed over those 10 or 11 years of playing first class cricket and being around some of the best players who have ever played cricket for Australia," he said. "Intuition really does come to the fore."
The other selection dilemma facing Australia ahead of the Melbourne test centres on the composition of its bowling attack. Mitchell Starc took a match-winning five-wicket haul in the first test but is in line to be rested either in Melbourne or in the third test at Sydney under Australia's rotational selection policy.
"It's about bowling loads," Inverarity said. "The science behind it is that they've got to build up their bowling loads so the oscillations are not very significant.
"If they do become reasonably significant, as they have done for Mitchell, then you enter a danger period, a high-risk period."
If Starc is rested in Melbourne, Tasmanian fast bowler Jackson Bird will likely make his test debut.
Meanwhile, Sri Lanka's preparation for the test has been harmed by the revelation of a rift between captain Mahela Jayawardene and his national governing body.
Sri Lankan cricket officials say Jayawardene and team manager Charith Senanayake breached their contracts by making public their concerns over the leaking of a confidential memo.
Jayawardene sent a memo to Sri Lanka Cricket last week suggesting fees from this year's World Twenty20 tournament should be shared with support staff, coaches and groundstaff - a request denied by SLC as it departed from established practice.
The memo and the SLC's response appeared in Sri Lanka's Daily Mirror newspaper, angering Jayawardene who wrote to the paper saying the leak had caused him to lose faith in the SLC.
Veteran Sri Lanka batsman Kumar Sangakkara will play his 115th test from Wednesday, but his first Boxing Day test at the MCG.
With 9,660 test runs at an average of 55.64, Sangakkara is placed second on the Sri Lanka all-time list behind Jayawardene who has 10,671 test runs at 49.96.
"If you're a batsman, 10,000 test runs is that separation between a batsman who will probably be remembered a bit more than the rest," Sangakkara said.
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