We'll find out plenty about Shane Watson if he takes over as captain of Australia in the Boxing Day test against Sri Lanka, Australia coach Mickey Arthur says.

The home side was on Monday night bracing itself for bad news after Michael Clarke was taken to hospital for scans on a hamstring injury the skipper suffered earlier in the day while scoring a brisk 57 in Australia's second innings.

The absence of Clarke - the leading runscorer in test cricket in 2012 - would be a hammer blow to Australia's hopes of winning the three-match series against Sri Lanka who will be confident of success in the Melbourne and Sydney tests on pitches assisting star spinner Rangana Herath.

Herath claimed 5-95 in Australia's second innings of 278.

Sri Lanka will resume on Tuesday's final day of play on 2-65, requiring a further 328 runs to win.

Sri Lanka's two all-time leading runscorers Kumar Sangakkara (18) and skipper Mahela Jayawardene (five) are at the crease.

Clarke managed to lead his side onto the field after the tea break on Monday and Arthur hinted the skipper would do the same on Tuesday.

"He will get all the treatment he needs," Arthur told a news conference on Monday night.

"He will get that after hours tonight and he will get that tomorrow between breaks.

"You would have to cut Michael's leg off for him not to be out there. He certainly wants to marshal the troops and he wants to be there if hopefully sometime we can clinch a win.

"We don't know exactly the extent of the injury just yet."

Australia will rely heavily on vice-captain and allrounder Watson on Tuesday with the ball and Arthur says the 31-year-old could face the biggest moment of his career on December 26.

"It (Watson as captain) is a distinct possibility," Arthur said.

"It would be a really good challenge for Shane. We'll learn a lot about Shane and his leadership ability.

"I'm confident he will come through it very well. If it does materialise, it will be a really good opportunity for him."

On a troubling day for Arthur, one of the challenges for his side is taking another eight wickets with a bowler short, after paceman Ben Hilfenhaus was ruled out of bowling again in the match and taking part in the Melbourne test with a side strain.

However the presence of pace-bowling allrounder Watson, who missed the Adelaide Test with a calf injury when

Australia narrowly failed to bowl out South Africa last month after quick James Pattinson broke down during the match with a side strain, is giving Australia extra hope of victory.

"The wicket is playing a little bit more deceptively now. I feel we are in a better shape in terms of our attack simply because we have 'Watto'," Arthur said.

"We only had two quicks and (spinner) Nathan Lyon in Adelaide, so the similarities I guess are there but full confidence that we have the attack that has an ability to get eight wickets."

Mitchell Johnson and uncapped duo Nathan Coulter-Nile and Jackson Bird are among the candidates for the Melbourne test squad following the withdrawal of Hilfenhaus.

Arthur named Brad Haddin, Usman Khawaja, Rob Quiney and Alex Doolan as possible contenders to replace Clarke.
Play is scheduled to start at 10.10am AEDT on Tuesday. 

- AAP