It looms as his best chance to make every post a winner as the Brumbies lock prepares to join Irish club Ulster at season's end.

The Brumbies are gearing up for the second leg of Super Rugby's most dreaded road trip as they prepare to fly to Argentina to meet the Jaguares next weekend.

A loss would almost certainly spell the end of their season but a victory would keep the Brumbies' slim finals hopes alive heading into the final six rounds.

History shows winning abroad is not beyond them - the Brumbies made the trek to South Africa and Argentina two seasons ago and returned with two wins in the kit bag.

But that was then. Today's crop have been struggling to find consistency in their performance for months after being riddled with injuries and forced Wallabies rotations.

So all they can do is throw caution to the wind - fitting given coach Dan McKellar has been backing his players to adopt a fearless approach this season.

"It's kind of a nothing to lose mentality. We just go out to play to the best of our ability and the result will take care of itself," Carter said.

"When we look back, we did this kind of trip a couple of years ago when we went to Port Elizabeth and then Argentina after that and we had two wins on the road then.

"If we come away with two good performances in South Africa and Argentina, then we build that momentum coming back, before we come home and play in front of our home crowd at [Canberra] Stadium. That'll give us a good run into the back half of the season.

"We just want to play the way we train and play the way we have spoken about. We've had patches throughout the year in which we have been good, but we have let ourselves down in other areas.

"Sometimes we have been really good for the 80 minutes. [The goal] is just consistently turning up each week and putting in a performance we can be proud of. That's what we're aiming for right now.

"It is what it is. Each week we've got to get up and play, prep the best we can. If we can do that week in, week out, then we will see the consistency. Sometimes it's tougher than just saying it."

Key Brumbies back-rower Lachlan McCaffrey's hopes of featuring on tour have been dashed after he failed to overcome a medial ligament complaint suffered the day before flying to South Africa.

McKellar had hoped he would be fit to play but instead McCaffrey was scheduled to be on a flight home over the weekend, with Jahrome Brown filling the void.

"Depth is something we spoke about in the off-season and at the beginning of the season. We wanted everybody to be ready to go if they were called upon. Jahrome has had a couple of cracks off the bench and done a great job," Carter said.

"[McCaffrey] has been around all week but he obviously copped an injury in that Lions game and they were hoping to get him right for the game against the Stormers but he got ruled out, so he is heading home."

The Brumbies could yet receive a massive boost ahead of the Jaguares game with David Pocock in line to return from a niggling calf injury.