Waratahs will be without Bernard Foley for a third successive Super Rugby match after the star fly-half was sent home from South Africa due to post-concussion symptoms.
Australia international Foley missed the opening two matches of the campaign after taking a blow to the head in pre-season
After travelling with Waratahs for matches against Lions, a 55-36 defeat on Saturday, and Sharks next Sunday, the 27-year-old has been ordered to return to Sydney for further treatment.
"We are taking no risks when it comes to his welfare. The best thing for him right now is to return to Sydney where he can have some more tests and hopefully, that will send him on the right course to improve," said coach Daryl Gibson.
"It's terribly frustrating for him at the moment, he desperately wants to be out on the field and he's just not quite 100 per cent.
"It's one of those things that a number of players have suffered in the past. It does improve with time, the unknown question is how long. Our hope is that he recovers quickly.
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"So we want to set him on a course of action that, in terms of trying to investigate further, if there's any other underlying problems.
"He's hanging in that zone where he certainly can't be cleared to play so we believe the best thing for him is to go back to Sydney.
"He's feeling very heavy in his head, low grade headaches, particularly in any form of exercise.
"He's been photosensitive during that time, so he's experiencing all the classic signs of post-concussion and the symptoms that go along with it."
There was some good news for Gibson, though, with Nick Phipps and Will Skelton expected to be fit for round three after sitting out against the Lions with respective ankle and hamstring problems.