Potchefstroom (South Africa), Feb. 19 : Injured Australian cricket vice-captain Michael Clarke is in doubt for the opening tour match against South Africa Board President''s XI beginning on Friday, but is likely to play in the Johannesburg Test.

Clarke, who is suffering from a back injury, was restricted to walking laps with team physio Alex Kountouris while the main group completed warm-up fielding drills at Senwes Park in Potchefstroom, Fox Sports reports.

The team then retreated to the nets for their opening training session for this week''s three-day game ahead of the first Test in Johannesburg from February 26.

Australia, who need to avoid defeat in the three-Test series against South Africa to retain the No. 1 ranking, are yet to name a team for the tour game in Potchefstroom.

"It''s a worry. He (Clarke) has missed a couple of games, had a long flight and we had to get straight on a bus to get here. He''s getting better every day," coach Tim Neilsen said.

"It''s a bit different to normal. It''s not his lower back from what I understand - it''s a different injury to what his normal problem is. We''re just being a bit careful because we don''t want to blow him out on the back of the plane trip and put him back another week and have real pressure on him to get ready for the Test," he added. (ANI)