Australia's captain, Michael Clarke, does not believe Mitchell Johnson is past his best, but he has conceded the selectors will face a tough decision on which fast men to play in the first Test in South Africa. Johnson picked up just six wickets at an average of 52.16 during the series in Sri Lanka this month, and was easily the least effective of the fast bowlers.

Peter Siddle's hard work in his only appearance, during the final Test in Colombo, earned him a four-wicket haul, while Trent Copeland was steady and promising in his debut series. Ryan Harris was the stand-out performer with 11 victims before he missed the final match through injury, and if he is fit for the Tests in South Africa in November, he will be an automatic selection.

That means there will be a squeeze of at least four men for three positions and the selectors, one of whom will be Clarke, face a difficult choice. Johnson has a good record in South Africa, but during the Sri Lanka Tests his angle across the right-handers and into the left-handers became predictable, although Clarke believed his strike bowler had toiled hard without luck.

"I don't think Mitch has lost his mojo," Clarke said after the draw at the SSC, which secured the series 1-0 for Australia. "I still think he's as good a strike weapon as there is in international cricket. I think he's a match-winner with bat and with ball, when he's at his best. Mitch has got some time now if he wants to go away, whether he gets away from the game or if he wants to work on some things.

"He still bowls good pace. I think he bowled well throughout this series and didn't have as much luck as a lot of the other bowlers. You would have seen a lot of play and misses off Mitch. Conditions didn't really swing as well - he got reverse swing - but I don't think you saw any bowler throughout the series swing the new ball all that much.

"Sidds was awesome, again, grabbed his opportunity, made the most of it. It's going to be interesting come the first Test in South Africa for all the bowlers to work out which three quicks, if we go three quicks, are the best three for that first Test match. Sidds has done himself nothing but favours but I still think Mitch is a huge player for us. I think anybody that thinks Mitch is past his best would be very silly."

One thing going in Johnson's favour is the memory of how he performed in South Africa on Australia's last Test tour there, in 2008-09. He was fearsome in the first Test in Johannesburg, swinging the ball appreciably, and finished equal with Dale Steyn as the leading wicket taker in a series won by the Australians.

The conditions in South Africa will be vastly different to Sri Lanka but there are unlikely to be any major changes to Australia's squad after their consistent performances over the past month. Clarke said he was proud of how the players had gelled together in their first series under a new captain, and in the shadow of the Argus report, which was released at the start of the tour.

"There's been a lot of stuff off the field as well that the playing group have had to deal with throughout this series," he said. "I think we've handled it really well so we deserve a lot of credit for that. Every single player has done nothing but grab their opportunity with both hands.

"You've got a guy running drinks in Usman Khawaja who batted like a genius the whole series, got a hundred in the tour match and was really unlucky to miss out in the (third) Test match. In regards to the cricket we've got coming up. We've got a lot of tough cricket. We've got to be ready for that as well. This is a great start. I heard that we're now ranked four in Test cricket, which is fantastic and I'm really happy with that but it's a long journey."