Durban - Stirling Mortlock has given himself 48 hours to prove his fitness, otherwise he'll stand himself down from Saturday's Super 14 rugby match against the Sharks in Durban.
The Brumbies outside centre suffered two corked thighs during the team's 25-17 loss to the Lions at Ellis Park at the weekend.
He has been able to complete only restricted training since. Mortlock ran at 70% on Monday and 80% on Tuesday.
The Brumbies have Wednesday off before their main training session of the week on Thursday.
Coach Andy Friend has always been a believer in having his starting team for the upcoming match training together at the execution session, so they can work on combinations.
And Mortlock said he wouldn't make himself a special exception, declaring he would rule himself out of the Sharks contest if his thighs weren't improving at a desirable rate.
"If I can't train with the team by Thursday then that'll be it, it all gets too hard from then so I'd put my hand up and sit the game out," he told The Canberra Times.
"To be honest it's still pretty sore so I've just got to let the rehabilitation take its course but I'm still not well enough to train properly yet.
"I'll see how it goes the next two days but I've been around long enough to know that if you're not right by the Thursday, you're generally not sufficiently right by game day and I won't jeopardise the team by giving myself too long before we make a decision." Mortlock was crunched in a sickening tackle in the second half of the Lions match last weekend.
There were initial fears he had suffered a serious knee injury after replays of the tackle showed his right side almost hyper-extending as a result of the clash.
Mortlock left the field when he found himself unable to take any weight on his legs.
"I wasn't too sure at the time what it was because both legs were in pain," he said.
"It was a pretty full-on collision. I'm doing everything possible to try and be right in time but I'm certainly not a guaranteed starter.
"I'm not kidding myself." Friend hoped his star back would recover sufficiently to take his place in the team for Sunday morning's crucial clash against the second-placed Durban outfit.
Mortlock has played every game for the Brumbies thus far this season.
"It would be a significant boost for us if Stirling was able to play because he's such an integral part of the team," Friend said.
"We won't play him if he's not right to play or if he can't train with the team all week because we want out execution session to be with the players who are playing." Should Mortlock fail his fitness tests, Friend would likely shift Adam Ashley-Cooper to outside centre, elevate Clyde Rathbone back into the starting team on a wing and bring Gene Fairbanks on to the bench.