Sydney, Oct 4 (IANS): Australian captain Michael Clarke Tuesday said that it will be tough to beat South Africa in their own backyard.

Australia are scheduled to play two Twenty20 Internationals, three One-day and two Test matches against South Africa starting Oct 13.

Clarke said playing in South Africa is one of the toughest challenge in world cricket. However, Australia won the 2009 Test series in South Africa.

"They are a very good team and they are ranked very high in all forms of the game," Clarke was quoted as saying by Sydney Morning Herald Tuesday.

"They have had a lot of success in their own country, so it is as tough a challenge as you face in world cricket, no doubt."

South Africa are second in the current Test rankings while Australia are currently lying at fourth place. In the 50-over format, Australia continue to remain at the top with the Proteas are sitting at fourth.

Clarke also cleared the air on the team's premier all-rounder Shane Watson batting slot in Tests.

"My mind hasn't changed since Sri Lanka. "Right now I think he is best for the team opening the batting and that is certainly where he will bat in South Africa."

"When we left Sri Lanka he was excited he made some runs at the end of that tour and got another hundred for Australia which is fantastic. He knows he has had some success over there, so I think he is pretty excited to get over there and bat in those conditions again.

Clake comments came after Watson expressed desire of moving down the batting order.