Khawaja's unbeaten 158 and Jimmy Peirson's rapid 89 not out steered the Bulls to 4-370 in their second innings at stumps on day three.

Khawaja began Sunday on 15 and batting for survival - the Bulls were 2-63, trailing SA by 65 runs.

He ended the day with his side 242 runs ahead and in the driver's seat to force a result at Adelaide Oval.

Khawaja's 31st first-class century also is a timely reminder of his talents ahead of the Ashes series against Engand, despite the 34-year-old falling out of favour since playing the last of his 44 Tests in August 2019.

The classy lefthander defied the Redbacks, who twice believed they dismissed him: in Saturday's last over, when on 13, he appeared to glove a ball to gully but was given not out.

And when 108 on Sunday, the Bulls skipper survived a confident appeal for caught behind after attempting to hook a short ball.

"You know I can't comment on decisions that have either gone our way or haven't gone our way," Redbacks coach Jason Gillespie said of the flashpoints.

Peirson, Test star Marnus Labuschagne (45) and Matthew Renshaw (41) offered able support to Khawaja.

Labuschagne - who hit his first ball for four but didn't reach the boundary again in his 179-ball stay - described Khawaja's knock as "an amazing innings".

"He really showed his versatility in the sense that he really absorbed the pressure for hours," Labuschagne said.

"After doing the hard work like that and then be able to reap the rewards this afternoon ... we have really flipped the game."

Khawaja and Peirson dominated the last session, amassing 165 runs from 38.3 overs with SA's Gillespie saluting their batsmanship.

"We probably let them off the hook a little bit in that last hour or so, ... but you have got to take your hat off to Usi and Jimmy, they played really, really well," Gillespie said.

"By and large, we bowled really well at them. So fair play to them."

Khawaja struck 12 fours and a six from 287 balls while Peirson cracked 13 fours and a six from his 132 deliveries.

SA Nathan McAndrew was the only multiple wicket-taker with 2-85 but the standout bowler was paceman Daniel Worrall, who claimed 1-37 from 28 overs.

Australian Associated Press