Emerging South African paceman Kagiso Rabada claimed three crucial wickets as South Africa closed in on victory against Australia on the fourth day of the opening Test in Perth on Sunday.

Set an intimidating victory target of 539, the home side were wobbling on 169 for four at stumps and facing a potential record defeat against South Africa.

Usman Khawaja was on 58 and Mitchell Marsh on 15, with South Africa's unbeaten record at the ground set to be extended.

An extraordinary piece of fielding by the diminutive Temba Bavuma removed the dangerous David Warner for 35 to end an opening stand of 52.

Warner dropped the ball in front of him and set off for a quick single, but Bavuma pounced from cover and unleashed a powerful throw while horizontal and still in mid-air.

It rattled the stumps at the non-striker's end with Warner centimetres out of his ground.

Four balls later, fellow opener Shaun Marsh (15) was caught at second slip by Faf du Plessis off the bowling of Rabada as Australia suddenly slumped to 52-2.

Steven Smith and Khawaja, who was dropped on 41 at first slip, set about rebuilding the Australian innings in search of a draw.

The pair settled in against the part-time bowlers, but when the ball started to reverse Rabada returned to the attack and ended a 92-run third-wicket stand with an impressive spell.

The 21-year-old showed he can become the perfect long-term replacement for Dale Steyn, who went off the field with a shoulder injury on the second day, when he removed Smith (34) and Adam Voges (1) in successive overs.

Smith had looked solid but drove at a ball and got an outside edge to wicketkeeper Quinton de Kock.

Rabada's next over to Voges was outstanding, with a couple of almost unplayable deliveries before he had the new batsman caught behind off a thin outside edge.

South Africa had declared their second innings on 540 for 8 after lunch when Philander was bowled by Smith for 73.

It ended a brisk 72-run stand with Keshav Maharaj (41 not out) as the visitors batted the home side out of the match after resuming on 390 for 6 on Sunday morning.

SCORES IN BRIEF

SOUTH AFRICA: First innings 242

AUSTRALIA: First innings 244

SOUTH AFRICA: Second innings 540 for 8 decl (Elgar 127, Duminy 141, Du Plessis 32, De Kock 64, Philander 73, Maharaj 41 not out; Hazlewood 2-107, Siddle 2-62, Marsh 2-77)

AUSTRALIA: Second innings 169 for 4 (Warner 35, Khawaja 58 not out, Smith 34; Rabada 3-49)