"He said, 'sorry to hear about the knee injury, head up, focus on your rehab. That's all you can do at the moment'," Carter said.

"So that's what I'll do.

"If you start worrying about everything that's going to happen in the future, you forget about what you're doing in the moment."

Walking with the aid of crutches eight days after his operation to repair a torn medial cruciate ligament, Carter's attitude towards the Rugby World Cup hasn't changed.

The 10-12 week recovery period puts him on the brink of being ready for the Wallabies tour of the US in September preceding the World Cup.

The Wallabies have their opening game of the tournament against Fiji at Millennium Stadium on September 23.

"Obviously I can't play for the Brumbies for the rest of the season, which is really disappointing, but my goal for making the Wallabies at the end of the year definitely hasn't changed," Carter said.

"The Wallabies are doing a tour to the US at the start of September and head to London at the end of September for the World Cup.

"It's obviously a tragic thing to happen, missing so much game time, but coming back from rehab and injury you normally come back in better shape than when you go into it.

"That's the way I'm looking at it."

The Brumbies would have desperately wanted to have Carter on the field at Canberra Stadium on Saturday taking on the Canterbury Crusaders instead of watching the game from the grandstand.

Carter's season came to a halt when Pretoria Bulls winger Bjorn Basson crashed into his right knee on May 30 in the Brumbies' 22-16 win.

"I knew there was something pretty bad that had happened, but the physios had a look at it and they thought it was just a lower-grade MCL, so they tried to strap it up and told me to play on," Carter said.

"As I started to run, I knew there was something wrong with it."

Since making his Super Rugby debut in 2011, the 25-year-old has become one of the leading second-rowers in the country with his work rate at the breakdown and in the lineout.

That led to his first cap for the Wallabies last year, the first of 11 appearances for Australia.

Carter's recovery is in good hands.

He underwent the knife in Brisbane on June 2 with renowned sports surgeon Peter Myers, who has operated on fellow Brumbies' David Pocock, Stephen Moore and Scott Fardy.

Carter is taking confidence from how he recovered from two serious injuries last year - the first a torn calf tendon that forced him to miss three weeks and an ankle syndesmosis when he was sidelined for two months.

"As bad as getting injured is, it can give you a chance to focus on other areas," Carter said.

"I plan to strengthen up and come back bigger and better."

What he hasn't got used to is being a spectator.

Carter would have been playing in his third straight finals series for the Brumbies, who have already booked their place in the top six.

At stake this weekend is a chance to win the Australian conference and an all-important home semi-final.

"I watched them for the first time last week and it's not something I'm used to," Carter said.

"Making the top two is very much in the back of everyone's mind.

"I've got no doubt the boys will put their best performance out on the field."