Brumbies and Wallabies winger Henry Speight is expected to be out of action for eight weeks and may need surgery for a bone fracture above his eye.
Speight suffered the injury when he collided heads with Brumbies team-mate Christian Lealiifano during his team's Super Rugby loss to the Stormers in Cape Town on Saturday.
X-rays revealed the extent of the damage, which is not only a blow for the Brumbies, who are leading Super Rugby's Australian conference, but also for Speight's preparation for Australia's Sevens campaign at the Rio Olympics.
He is a relative newcomer to Sevens and, by the time he returns, there will only be two rounds of the Sevens World Series remaining before the Rio Games.
Speight was returning to Canberra on Tuesday to meet with surgeons who will assess the damage.
"It's a shame to lose Henry, he's obviously a world-class winger," said Brumbies coach Stephen Larkham.
At this stage it looks like he may be out for eight weeks but we will have to wait for further advice."
Brumbies winger Lausii Taliauli was flying to South Africa to replace Speight in the tour squad as they prepare to play the Cheetahs in Bloemfontein this weekend.
"We also have Nigel Ah Wong, Robbie Coleman and James Dargaville here now and a decision on Henry's replacement for this Saturday's match will be made later this week," added Larkham.
"With Henry's commitment to the Australian Sevens program this year we knew we were going to have to make arrangements for his absence.
"While the injury isn't ideal, it is something we've planned for."
The Brumbies have now had to replace Andrew Smith, Jarrad Butler, Speight and Josh Mann-Rea on their three-week road trip due to either injury or suspension.
Smith has had an ongoing foot injury and was ruled out of the match in Perth against the Western Force following the captain's run, Butler suffered a knee injury at training in Cape Town this week and Mann-Rea has been suspended for one-week for punching an opponent in the loss to the Stormers.
The Brumbies return home after playing the Cheetahs on Saturday before taking on the Chiefs at home on April 2.