Spin-bowling allrounder Ashton Agar and opener Matthew Renshaw were called up to the Australia squad Friday for the third Test against South Africa with Cameron Green and Mitchell Starc ruled out injured.

Pace spearhead Josh Hazlewood, meanwhile, has recovered from a side strain that kept him out of the last two Tests and is expected to play in Sydney next week.

Australia has already won the three-Test series after a six-wicket victory at Brisbane and by an innings and 182 runs in Melbourne.

Green, who didn't bowl in South Africa's second innings in Melbourne, has a fractured right index finger.

Starc bowled 18 overs with a bruised and bloodied finger that officials have now revealed was also fractured.

Both players will be sidelined for weeks and are racing against the clock to be ready for Australia's blockbuster Test tour of India in February.

"Ashton offers a second spin option should the Sydney pitch be conducive to turn, as it has done in the past. He also brings a solid batting component," said selector Tony Dodemaide.

"Matthew is included as a versatile batting option who is in good form, including an unbeaten century in the recent PM's XI tour match against the West Indies."

Renshaw has played 11 Tests, but not since 2018 against South Africa, while Agar has featured four times, with his last Test in 2017 in Bangladesh.

With Hazlewood recovered from a side strain and the uncapped Lance Morris -- touted as the most exciting fast bowler in Australia -- also in the squad, selectors have plenty of options.

"In terms of fast bowlers, it's a blessing to have Josh returning, while Lance offers a genuine point of difference with his raw pace and skill," said Dodemaide.