Sydney - Wallaby back Berrick Barnes is worried another knock to the head playing for Vodacom Super Rugby's Waratahs could rule him out for the rest of the season.
Barnes will miss this weekend's derby against the Perth-based Western Force after suffering concussion from an elbow to his head during a match against the Brumbies a fortnight ago.
It was the second instance of concussion for Barnes in a month. The flyhalf, who routinely wears protective head-gear during games, was also concussed during the Waratahs' second-round defeat of the Brisbane-based Reds in February.
"I have had a couple of concussions in a row, and I've had a history of them. At the moment, I don't feel right," Wednesday's Sydney Morning Herald quoted Barnes as saying.
"The reality is if I get hit in the head in the next coming week, we're talking months (off) to the whole season.
"I am not concerned long term at this stage, but it has been brought to the forefront, the risks with head injuries, and it could potentially curtail my career, and that is not what I want."
The versatile Barnes, likely to be picked for the Wallabies World Cup squad, said the concussion had him still struggling to exert himself at training and added he would not be rushing to put his hand up for selection.
"Just trying to run, it has affected me," said the 24-year-old, who has played 31 Tests for the Wallabies.
"Until (the medical personnel) clear it up, only I will know when that is, but it is hard to lift weights.
"I had (a concussion) in 2009, and I was fine to come back then. I have just felt a bit more after this one.
"You take all the medical reports, everything into it, and I am not going to be stupid. The season is longer now, it is a 1 500 metre event rather than a sprint now.
"I am grateful that the Waratahs have also taken a safety-first view."