Australia duo Mitchell Starc and Mitchell Marsh are expected to be fit for the third Test against South Africa after coming through training unscathed on Tuesday.

Starc has been struggling with calf injury, while all-rounder Marsh suffered a groin strain during the Proteas' victory in the second Test in Port Elizabeth.

Both players look set to take their place in the side at Newlands on Thursday, having been put through their paces in Cape Town.

"By all reports he [Starc] is right to go," spinner Nathan Lyon said. "I heard Cameron Bancroft saying he was bowling quite quick. 

"That's exciting to have him up and going. I know the bowlers are feeling fresh after a couple of days off. 

"It's been a big summer for them but to have a couple of days off in the lead in to two massive Test matches is pretty exciting. 

"I got no doubts about Starcy."

The four-match series is level at 1-1.