All Blacks and Hurricanes stalwart Conrad Smith may be forced to rethink his glittering career after yet another massive knock left him unconscious for just under a minute.
While officials adopted a 'wait and see' attitude, Smith has previously said that he would reconsider his future if he suffered regular head knocks.
And a medical adviser for the Neurological Foundation has said Smith might have to take a year out from the sport - or give up altogether.
The 31-year-old Hurricanes centre was knocked out cold during yesterday morning's 48-14 loss to the Bulls in Pretoria.
Although scans cleared him of a neck injury, the effect of being unconscious for at least 45 seconds will take its toll.
This is not the first serious head knock the All Black has suffered. He blacked out during a match in 2010 and only six weeks ago failed a pitch-side concussion test after an onfield collision.
Though Smith later said he did not think he'd been concussed, he confirmed he'd been "stunned" twice during the match. He also said he would have major concerns if they became regular.
In the latest knock, Smith was unconscious before he hit the ground after putting his head on the wrong side in a tackle.
He regained consciousness after being taken to the sideline and rejoined his team at their hotel after being discharged from hospital.
The team doctor was assessing him last night to establish whether he should return to New Zealand a week before the rest of his Hurricanes team-mates.
Coach Mark Hammett said it was impossible to judge how long his skipper would be out of action for, but confirmed he wouldn't be considered for the next match.
Neurological Foundation medical adviser Jon Simcock said any sportsman who sustained repeated concussions should think about giving up their sport.
The prognosis for any sportsman depended on how long it took to recover from the knocks, how long it took to regain consciousness, full brain function, the ability to concentrate and the absence of drowsiness and headaches.
If Smith recovered quickly the chances of brain damage were low, but if it took days then he should be stopped from playing rugby for a year, Dr Simcock said.
Rugby Union medical director Ian Murphy said rugby abided by international guidelines for the handling of head injuries.
"The most important thing with any injury and the biggest risk factor is to not fully recover and clearly now for Conrad we must ensure he is fully recovered to everyone's satisfaction from this episode."
'In good hands'
Conrad Smith's mother is relieved she didn't watch the game where a neck-crunching tackle left her son unconscious for nearly a minute from a severe concussion in Pretoria.
"Thank goodness I didn't ... This is something every mum doesn't want to see," Marian Smith said yesterday after her son was put in the recovery position on the South African field.
She had since received a text message from Smith saying he was "OK and in good hands".