Springbok coach Peter de Villiers has moved swiftly to defend his decision to name Ruan Pienaar, initially his preferred choice as flyhalf, at fullback for the Tri-Nations crunch Test against Australia in Perth on Saturday.

The Sharks utility back has replaced Frans Steyn in the only change to the starting XV.

Schalk Burger returns to the bench, in place of the injured Danie Rossouw, in the only other change to the matchday 22.

But it was the decision to name Pienaar at No.15 that raised some eyebrows especially after De Villiers recently stated that Pienaar is now being considered only as a flyhalf.

The 24-year-old Pienaar has only started at fullback for the Boks twice before - against Tonga at the 2007 World Cup and Wales on the year-end tour in 2007.

The first eight of his 32 Tests were all off the bench and he has made another 10 appearances off the bench - often playing at fullback.

In 2007 he also made four starts as a scrumhalf, while he started at flyhalf in six of his last eight Tests - in the other two he played off the bench.

De Villiers, though, insists that the latest decision was made simply to keep all his players happy.

"Ruan is a brilliant player," De Villiers told a media gathering in Perth, adding: "Both Ruan and Frans are very talented young players.

"I hope he will add more bite on attack. Frans Steyn has not let us down, he always pulled his weight, but it's important to keep the interest levels high of everyone in the squad.

"We are very organised at the moment, we don't want to become a fruit salad, so No.15 will be Ruan's number and No.10 will be Morne's number.

"Most of the time, that will be the case, but we have very versatile players as we saw in the last game when the No.3 [captain John Smit] put through a brilliant grubber which No.5 [Victor Matfield] chased down on the wing, so you never know what might happen in the game."

Asked whether Pienaar might switch to flyhalf from time to time during the game, he said: "Ruan has been selected to play at fullback and that is where he will concentrate his energies.

"However, if the situation dictates, as it might, we have an option to make use of him at 10."

Burger's availability is also a welcome return for the Boks, following his eight-week ban for a facial massage on B&I Lions wing Luke Fitzgerald during the second Test against the Lions in Pretoria.

"Heinrich [Brussow] has earned his spot, and what a pleasure it is for the team to have a player of Schalk's calibre giving us a boost off the bench," De Villiers said.

"Heinrich Brussow has done well in that position," captain John Smit said of the decision to start Burger on the bench behind the rookie flank.

"But it is great to have a player like Schalk ? with 50 caps ? on a very capable bench.

"It's certainly indicative of where our team is at the moment to see Schalk at No.19," Smit added.

"It shows how far the team has come. It's amazing to have a bench like that."