McCabe, 24, has recovered from a stress fracture in his foot that kept him out of Australia's first three games of the tournament.
"He hasn't been off for long, and obviously he's had a full season of rugby, so he's well conditioned," he said. "He played throughout the June series and then finished off Super Rugby as well, so he's got good background with us. We've got no doubts about his fitness, it was just a small fracture which has obviously healed fully now."
The ACT Brumbies centre returns to the international stage on the back of just half an hour of club rugby for Wests in Canberra's first grade grand final at the weekend.
His return means that Kurtley Beale has been relegated to the bench, with Berrick Barnes shifting from inside centre to full-back to accommodate him.
Deans was also not worried by Barnes' lack of experience at Test level at full-back, having played there for Sydney University last year.
"There's nothing in there that he hasn't done before. All the skills and requirements, he's perfectly capable of fulfilling," he said.
McCabe said the transition from local club rugby to the highest form of the game will be a "big jump", but one he feels capable of clearing successfully.
"It's a huge vote of confidence from Robbie, that he thinks I can come back and play well straight away," he said.
"I really do appreciate that and I hope I can return the favour by playing well. It's obviously a big jump coming from Canberra club rugby to Test rugby, but physically I feel good and I'm ready to go."