Doubts over flyhalf Stephen Larkham's availability for the Wallabies' upcoming European tour could fast track the world champion's entry into their much-talked about new era.

The international retirement of veteran centres Tim Horan and Jason Little, prop Richard Harry and flanker David Wilson at the end of this year's triumphant Tri-Nations series sparked plenty of speculation on the Wallabies' future.

Tuesday's withdrawal of halfback George Gregan from the tour due to injury further depleted the squad and with doubts over the fitness of Larkham, the Wallabies will be running out a new-look backline on the four-game tour starting on October 28.

Gregan's injury allows for the return to the Wallaby squad of Waratahs halfback Chris Whittaker, who will battle the Queensland Reds' Sam Cordingley for the starting spot on tour. Cordingley sat on the bench for all of the Wallabies' seven Tests this season, but some strong Sydney club form with Randwick ensures that Whittaker will provide a serious challenge in Europe.

"Going back to club rugby for Randwick and getting more ball in the hand certainly helped my confidence a bit," Whittaker told AAP. "George is the best halfback in the world and you don't have much opportunity to take over from him.

"But now it's me and Sam Cordingley there and I suppose he's starting in front but hopefully I can knock him off."

Wallaby coach Rod Macqueen accepted his side could be ripe for the picking after their successful year.

"More than half our team has changed and we've probably only got a third of our team left from the World Cup," Macqueen said. "So we are going through a new era but it's part of the evolutionary process.

"You just have to try and keep as much experience in the side as possible."
The short tour starts on October 28 against a French Barbarians side at Bayonne, followed by a World Cup final rematch against France at Stade de France on November 4; Scotland at Murrayfield on November 11 and finally England at Twickenham on November 18.