Clarke's fitness race turns into a jog

Sydney - Barring any further setbacks, it appears that Michael Clarke's return to full fitness and the captaincy of the Australia Cricket World Cup team is now a matter of "when" rather than "if".

The 33-year-old batted, bowled and fielded in an outing for a Cricket Australia XI in Brisbane on Thursday and looks certain to prove his fitness by the deadline of the co-hosts' second pool match against Bangladesh on February 21.

Giving another in what have become almost daily updates on his recovery from a torn hamstring, Clarke on Friday referred questions of whether he would also be fit for Australia's tournament opener on February 14 to the team's medical staff.

"I don't know the answer to that question," he told reporters in Adelaide.

"I have been following (the medical team's) guidelines from day one and I'm extremely thankful and grateful that I sit in this position now because of their advice and guidance.

"I will 100 percent be dictated by what they feel and believe."

Clarke's diplomacy was an indication that there was perhaps an element of truth in the view that the peremptory February 21 deadline was something of a slap-down for the Australia skipper.

Rumours of splits between Clarke and Cricket Australia, selectors and even his team mates have been widespread in local media for a couple of weeks.

Clarke is hoping to feature in a practice match against the United Arab Emirates at the Melbourne Cricket Ground (MCG) next Wednesday, which would make him almost certain to face England in their World Cup opener at the same ground three days later.

Doubts over Clarke's fitness have also ignited a fever of speculation over who would replace him as skipper should he not be available for the tournament.

George Bailey would normally be expected to step up from the vice-captaincy but many in Australia support the elevation of in-form batsman Steve Smith, who led the test side to a series victory against India over the New Year in Clarke's absence.

Given team physiotherapist Alex Kountouris has said that Clarke's degenerative back problem means he could break down with another hamstring injury at any time, that discussion could have plenty of mileage in it yet.

If fully fit, though, there is no doubt that Clarke's leadership and batting could have a major bearing on whether Australia can win a fifth World Cup title on March 29.