Opener Usman Khawaja and number three Marnus Labuschagne guided Australia to 147-2 before bad light and rain interrupted day one of their third Test against South Africa.

Winning the toss and choosing to bat first, the hosts found themselves 12-1 in the fourth over after David Warner edged to first slip off Anrich Nortje's bowling.

Khawaja showed no signs of joining Warner in the sheds, patiently making his way to 54 not out off 121 deliveries for his 21st Test half century in his 99th innings.

Play was interrupted just after 2pm local time due to bad light, and 30 minutes later the rain arrived. After over two hours, play resumed, but they were only able to sneak in another four overs before deciding the light was insufficient.

South Africa will be glad they were able to play that late mini-session, claiming the wicket of Labuschagne with the penultimate ball of the day in the 47th over.

Labuschagne had come in and steadied the ship, adding 79 runs off 151 deliveries after surviving two reviews – with a bit of glove negating an lbw shout, and a near catch in the slips bouncing just in front of the fielder.

His day ended when Nortje found his outside edge with a short delivery, allowing both teams to head into the pavilion with positives to cling to.

SCG a happy hunting ground for Khawaja

Khawaja came into the contest boasting an average of 98.3 from his nine Test innings at the SCG, and he boosted that figure to 107.3 by the close.

For his career, Khawaja is averaging 52.3 runs in Australia, which is dramatically higher than his averages in South Africa (24.2) and England (19.7).

Up-and-down Warner provides selection headache heading into Ashes season

While Warner will feel he has done his job this series, averaging 52.3 from his four innings as Australia push for a 3-0 sweep, his opening spot is still up for grabs for this year's Ashes campaign.

His average this series is buoyed by his terrific 200 in the second Test, but the 36-year-old's other three innings have resulted in scores of nought, three and 10.