Steven Smith faces a fitness test on his troublesome neck ahead of Australia's Test series decider against South Africa in Cape Town, while Nic Maddinson's omission from the game has been confirmed. The opening batter is flying back to Australia to be available for New South Wales' next Sheffield Shield game starting Friday.

Sam Harper, who was called up as wicketkeeping cover when Josh Inglis suffered a fractured finger, is also leaving the tour in order to be available for Victoria's next Shield match against Queensland starting on Saturday. Inglis has been cleared to resume wicketkeeping should Alex Carey suffer any issues.

The axing of Maddinson, who made 0, 48, 0 and 8 across his four innings in the series after his shock recall means that Matt Renshaw is set to return to the top of the order to partner Travis Head.

However, the most significant aspect playing out for Australia's final XI is the fitness of Smith, who was hampered by a neck problem in Gqeberha and will need to get through a full net session on Monday. He only batted for 15 minutes on Sunday against side-arm throws from Michael Di Venuto without wearing his helmet.

"We feel like it's going to be a pretty steep progression in terms of [whether] he should be available," head coach Andrew McDonald said. "But if we're surprised today, you'll see that play out."

If Smith wasn't able to take his place, it would likely ensure that Marnus Labuschagne keeps his spot amid the debate around his future at No. 3. The selectors were meeting to pick the XI on Monday morning ahead of the team's final training session at Newlands in the afternoon.

"I don't know if I've got anything further to add than I think everyone's said over the last [period of time]," chair of selectors George Bailey said of Labuschagne. "We've seen some good things. Is there a block at the moment around the 30s? Yes. [He's] still contributing in terms of his ability to get through a number of balls.

"So it's a decision around what does that look like if he gets through [to the 30s] again, what does it look like for the collective and is it helping others around him [and] the team get a result that we ultimately want?"

Bailey, meanwhile, continued to stand by the decision to call up Maddinson for the tour and insisted the experience in South Africa would not have to mean the end of his Test career.

"I think performance-wise… would you like more runs in it? Yes. So that's okay," Bailey said. "It did allow us to set the rest of the team up the way that we wanted to whilst we were working with the group we have, yes.

"We always talk about what do we see when we see players that are best. I think you saw a glimpse of that in the second innings in Durban. So there's a message for him. With him going home, I wanted to be clear to him it wasn't a stopgap and that's it and it's a discard.

"The same reasons and process we worked through to get him to be on the table for here and ultimately to play, they'll be the same questions that we'll ask across the home summer to India as well."