CAPE TOWN : Mitchell Starc said a "reset at lunch" led to an Australian fightback after South Africa made a flying start on the first day of the third Test at Newlands on Tuesday.

Starc finished with six for 72 as South Africa were bowled out for 329 shortly before the close in a match which will decide a series between the two leading Test nations.

It was a performance which looked unlikely as South Africa raced to 140 without loss at lunch after being sent in.

Starc was one of the bowlers punished, with the tall left-arm pacer conceding 39 runs in seven overs, including four successive boundaries by Marques Ackerman, who went on to score a rapid 95.

"We probably expected more out of the wicket," said Starc. "It was quite slow, with tennis ball bounce. They came at us hard.

"We didn't have our best stuff in the first two hours but the last two sessions were right up there. It's what we expect from this group. We had a reset at lunch and just tried to change the momentum in the field."

Ackerman, playing in his second Test, took the fight to the Australian bowlers with some dazzling strokes.

The slightly-built left-hander was on 82 not out at lunch, scored off just 75 balls.

He attacked veteran off-spinner Nathan Lyon, dancing down the pitch and hitting him over the stand at midwicket for six. But he tried one shot too many after lunch and was stranded when Lyon pushed the ball wider, giving Alex Carey an easy stumping.

Ackerman, 30, said South Africa would probably have been happy if they had been offered a total of 329 before play.

But he admitted: "We probably left a few runs out there."

Ackerman, who won a place in the side through strong domestic performances and some big scores for South Africa A, including 256 against Bangladesh A in August, is not normally an opening batsman but said he was not troubled by the adjustment.

"I have quite often had to face a new ball in my career and playing against our own fast bowlers in the nets has been good preparation," he said.