Sheehan temporarily lost his vision and was taken to hospital after Wallabies skills coach Scott Wisemantel hit him in the eye with a tackle bag during a training session in Canberra on Thursday, but on Friday he was cleared of any serious damage.

The Wallabies coaching staff would have breathed a massive sigh of relief having already lost reserve halves Sam Cordingley (foot) and Josh Valentine (ankle) to injury.

Sheehan is now favoured to be captain George Gregan's back-up for the third Bledisloe Cup clash with New Zealand in Auckland, although 19-year-old Josh Holmes is also in contention.

Holmes impressed during the Young Wallabies IRB Under-19 World Championship campaign, particularly against Scotland when he ran in three tries.

But he is yet to play a Super 14 match for the NSW Waratahs, and Wallabies fly-half Stephen Larkham feels it would be too big an ask to bring someone so inexperienced into the Test side.

"The step up from Super 14 to Test level is quite a big step and to not even have played Super 14 level is going to be a big ask to try to step up and play Test level," Larkham told the ABC.

"But it is whether they have confidence when they run out on the park and it is whether the players around them have confidence in them as well."

Western Force halves Chris O'Young and Matt Henjak are also possibilities to be called up to the Wallabies squad, as well as 22-year-old Luke Burgess of the ACT Brumbies.