We have to be at our best' - Clarke

Michael Clarke passed his first examination as Australia's captain by leading the side to a series victory in Sri Lanka, but he knows repeating that success in South Africa will be a major challenge. Clarke flew out of Sydney on Friday to join the squad ahead of the three ODIs and two Tests, after Cameron White's Twenty20 side kicked off the trip with a victory in Cape Town on Thursday.

And while that was an encouraging start, it's the Test matches that Australia really need to win as they attempt to climb back up the Test rankings, having risen from fifth to fourth following the Sri Lankan trip. Clarke's men will take comfort from their success in South Africa in 2008-09, when they took the series 2-1 under Ricky Ponting. Beating the second-ranked South Africans again would be a wonderful achievement for a developing side.

"South Africa are a very tough team in any form of the game - especially in their own backyard, so [a win] will be a great achievement," Clarke told reporters in Sydney. "We have to be at our best against South Africa, individually players know that and as a team we've got to be flying, with the bat, with the ball and in the field. We have to be as good as we can possibly be to win this one-day series and hopefully win the Test series as well."

The Test squad has not yet been named but the offspinner Nathan Lyon is expected to play a key role during the series after making a positive start to his international career in Sri Lanka, where he took five wickets on debut in the first innings in Galle. Clarke believes Lyon - who has played only eight first-class games - will be an important man over the coming months as Australia face South Africa, New Zealand and India in Test series, but he also stressed the need to manage his workload.

"He's a wonderful talent, as I thought before I went to Sri Lanka, and having seen him bowl, he's got beautiful shape out of his hand, he's got great natural variation, great change of pace," Clarke said. "He's young and inexperienced, though, and it's going to take some time and we have to look after him now and build him into the series in South Africa. Hopefully he can play a part in the practice game but with a big summer ahead in Australia ... it's about monitoring him.

"His body got tired at the back end of that Sri Lanka series with three back-to-back Test matches plus a tour game. We have to keep an eye on that, but he's a huge talent and hopefully he will play a huge part for Australian cricket."

And while Australia are coming off a busy period, with some players heading to the Champions League T20 after the Sri Lankan tour, South Africa will need to shed their rust after a long lay-off, having played no Tests since January. Clarke said South Africa's long stretch without cricket, as well as a finger injury to AB de Villiers, would help Australia, but he believed they would begin to find their touch during the ODIs, which start in Centurion on Wednesday.

"The T20s and one-dayers will help them get momentum as a team, even though there will be some changes for the Test team," he said. "I think AB de Villiers is a big loss for them as well with his injury. I think we should be high on confidence after winning in Sri Lanka but saying that, they are playing in their own backyard. It will be a great challenge for us. They are a wonderful team and they are always hard to beat."