The Brumbies lock has been named on the bench to take on the USA Eagles in a one-off Test at Chicago's Soldier Field, having played just two National Rugby Championship matches since the end of May.

Even when Carter went down with a torn medial ligament and a fracture in his knee, he never lost sight of the World Cup, which starts for the Wallabies on September 23.

"Ever since I did the injury … I was just thinking about how quickly I could get back and I've done everything I could to get back, I've played two games and it's feeling really good," he said.

"It was tough at times – coming to training was tough, but I always thought I'd be back ready to go around this time. I set myself a goal and we got there."

The 25-year-old made his return to rugby two weeks ago with the NSW Country Eagles in the NRC – and while not being named in the Wallabies 31-man World Cup squad, he earned a call-up for the US tour.

"I'd been training with the Wallabies for about two weeks before the [World Cup] squad got announced. Obviously I wasn't doing everything, I was doing my rehab and just being part of the squad and sitting in the meetings.

"After the squad got announced, I got the call saying would I like to come over and be part of the extended squad touring America and I jumped at the opportunity."

That invitation came after Carter got through 40 minutes of game time in the first round of the NRC, and he flew to the US last Sunday, a day after the rest of the team, having played against the Canberra Vikings on Saturday for some more time on the field.

The Wallabies spent the best part of a week at the University of Notre Dame, promoting the game and training in the "stinking hot" conditions, and moved up to Chicago on Thursday ahead of the Test.

"I don't think they know a lot about Rugby over here, but anyone who notices who we are are very genuinely curious, so it should be a great spectacle out at Soldier Field," Carter said.

As for the World Cup, Carter knows he is only an injury away from a call-up.

"I've put myself in a position where I've done everything I can to be available for it ... and I'm still training as hard as I can, so if the opportunity arises, then I'll be ready to go."

While he can continue training with the squad next week, once they leave for the World Cup it's an unknown story.

"When the squad goes to England ... anyone outside of the [named] 31 is not allowed to be in the same country as the squad, so I'm just looking to see what happens from there."

Three other Brumbies players have been named in the Wallabies side to take on the USA Eagles. Henry Speight will start at outside centre, while Joe Tomane has been named on the wing and Scott Sio will join Carter on the bench.

Wallabies v USA Eagles: 9.30am Sunday (AEST), Fox Sports 2