Australia [Images] skipper Ricky Ponting [Images] expressed surprise that Ashwell Prince [Images] declined the chance to captain South Africa [Images] in the third and final Test starting on Thursday.

"When opportunities come around like that I think any Australian would grab it with both hands," Ponting told reporters on Wednesday.

South Africa, 2-0 down in the series, initially offered middle-order batsman Prince the captaincy after Graeme Smith [Images] was ruled out by a broken finger.

However, Cricket South Africa later said Jacques Kallis [Images] would take the reins "to allow Prince to concentrate on his new position of opening batsman".

Ponting said the home side were bound to miss Smith in Cape Town.

"We're very keen to try and make it 3-0 and they will be without Graeme Smith, their captain and one of the best batsmen in the world," said the Australian.

"You'd think it would hurt them, one of them not wanting to be captain and them having a reluctant captain."

Kallis, though, played down the leadership issue.

"Ashwell had his reasons why he didn't want the captaincy and after he turned it down I was phoned and was happy to accept," said Kallis.

"There's no big issue about it. The guys have all got together and there is no tension ... the whole thing has been blown out of proportion."

South Africa are expected to hand first caps to opening batsman Imraan Khan and all-rounder Albie Morkel, 27.

Left-hander Khan, 24, hit 100 against Australia in a tour match at Potchefstroom last month.

"He played well but we knew very little about him then," said Ponting.

"We've picked his technique to pieces over the last few days and now we just need to execute our plans against him from the start to make sure he does not get away."

Australia have an excellent record at Cape Town, with nine wins in 10 Tests, but may bring leg-spinner Bryce McGain into their team on a pitch likely to turn later in the game.

Squads:

South Africa - Imraan Khan, Ashwell Prince, Hashim Amla [Images], Jacques Kallis, AB de Villiers [Images], JP Duminy [Images], Mark Boucher [Images], Albie Morkel, Paul Harris, Dale Steyn [Images], Makhaya Ntini [Images], Wayne Parnell.

Australia - Phillip Hughes, Simon Katich [Images], Ricky Ponting, Michael Hussey [Images], Michael Clarke [Images], Marcus North, Brad Haddin, Mitchell Johnson [Images], Peter Siddle [Images], Ben Hilfenhaus [Images], Bryce McGain, Andrew McDonald, Nathan Hauritz [Images], Doug Bollinger, Brett Geeves.