Pulu was rushed to The Canberra Hospital on Friday night after a head clash with Billy Meakes in the opening 10 minutes of his Brumbies debut.

It left him with a fractured cheekbone and shattered his hopes of launching a Wallabies audition for the World Cup after leaving New Zealand at the end of last year.

The lightning-quick winger will likely have an operation on Monday and will be out for at least six weeks, but his time on the sideline could be extended depending on how bad the damage is to his cheekbone and eye socket.

News of Pulu's injury made the Brumbies' changerooms even more sombre after a loss to the Melbourne Rebels 34-27 and was compounded by Henry Speight (hip) and David Pocock (concussion).

All three are set to miss the game against Pulu's former team, the Waikato Chiefs, next weekend and the Brumbies will have to find replacements.

Andy Muirhead, Lausii Taliauli and Chance Peni are set to compete for the two wing spots, but it is hoped Pulu will be back by the middle of the year.

"As a back line, and especially the back three [positions], we've really bonded in the off-season," Muirhead said.

"[Pulu] is a huge loss. He's electric, hopefully it's not too bad. All of the boys will get around him.

"We're shattered for him, pretty upset. We've got a game next week that we'll have to look forward to but we're obviously going to get behind him.

"I guess the good thing is there's so much competition, there were some tough decisions for round one and we're just lucky we've got guys who can step up and fill positions."

Pulu left the Chiefs to link with the Brumbies as part of a wider plan to force his way into the Wallabies.

The 30-year-old late-bloomer is regarded as one of the fastest players in Super Rugby and was invited to a Wallabies camp earlier this year before playing a game for the Brumbies.

He made his debut for the Chiefs in 2016, but this year was the first time he had been injury-free for the opening game of a season.

"Shattered. [Pulu] just can't take a trick. We'll see how he goes, he's been such a great addition to the club. He's really popular in the group, has a lot of experience and knowledge," said Brumbies coach Dan McKellar.

Speight will manage his hip problem, but he also had to leave the field in the second half of the loss to the Rebels.

The lack of wingers meant the Brumbies had to reshuffle their back line, with flyhalf Wharenui Hawera moving to fullback and Tom Banks shifting to the wing.

Taliauli injured his knee in the last pre-season game, but is expected to be available for selection for the game against the Chiefs. Peni will also be waiting for another Super Rugby opportunity after back to back suspensions ruined his season last year.

"We've got plenty to work on. There were a few crucial moments that we let slip and that hurt us a lot. Our set piece was unreal, we just need to finish that off," Muirhead said.

"If I get thrown into the starting line up I'm very confident I can perform, we'll see what happens and hopefully [Speight] is good to go as well."

Pocock is in danger of missing the match as he recovers from concussion, but Tom Cusack is a more than capable replacement in the back row.

SUPER RUGBY ROUND TWO

February 23: ACT Brumbies v Waikato Chiefs at Canberra Stadium, 7.45pm. Tickets available from Ticketek.