Glenn McGrath, Adam Gilchrist [Images] and Brett Lee [Images] have been left out of a 12-man Australian squad to play South Africa in a one-off Twenty20 international next week.

Australia's chairman of selectors Trevor Hohns said the trio were being rested to give them a short break between the Test series and triangular one-day series with South Africa and Sri Lanka [Images].

"Twenty20 cricket is still a bit of an unknown to us but we have tried to keep as much of the one-day squad together as possible," Hohns said in a statement.

"Having said that, Brett Lee, Glenn McGrath and Adam Gilchrist have not been selected in order to enable each of them to freshen up before the (one-day) series.

"Brett, Glenn and Adam have worked particularly hard during the Melbourne and Sydney Test matches and we want to manage each of their respective workloads carefully."

Hohns also announced that Mike Hussey had been promoted to vice-captain in the absence of Gilchrist, reflecting his growing importance in the team.

"He has done an excellent job in the one-day format and we have every confidence that he has the necessary ingredients to take on this additional responsibility," Hohns said.

The Twenty20 match will be played in Brisbane on January 9. The one-day series starts four days later.