David Warner crushes Proteas with majestic 200

An emotional and exhausted David Warner retired hurt after a majestic 200 as Australia dominated day 2 of the second Test on Tuesday and South Africa wilted in a Melbourne furnace.

Australia were 386 for three, in reply to the visitors' first innings 189, with a lead of 197 runs and the series at their mercy after the six-wicket win in the Brisbane opener.

Short of runs and without a century in nearly three years, a tiring Warner slogged his way to his third double-hundred from 254 balls before succumbing to cramps and limping off the Melbourne Cricket Ground field with the aid of a trainer.

On the way to his 25th hundred, the 36-year-old opener became the eighth Australian to reach 8,000 Test runs, while ending the debate about his place in the side.

Australia No 5 Travis Head was 48 not out at stumps, with wicketkeeper Alex Carey on 9.

Warner and Steve Smith put on a 239-run stand for the third wicket before Smith was caught in the gully for 85 off the bowling of paceman Anrich Nortjé.

It was the only wicket taken by a bowler on a dismal day two for the Proteas, with Marnus Labuschagne run out for 14 after Australia resumed on 45 for 1 in the morning.

Adding insult to injury, Nortje was knocked over by the host broadcaster's "spider cam" after lunch, the mobile, cable-suspended camera that takes aerial shots over the ground.

Warner brought up his first hundred by pulling pace spearhead Kagiso Rabada to the fine leg fence and he celebrated wildly, blowing kisses off his bat as the terraces roared.

On 124 he lay down by the pitch to have trainers work on his cramped legs, but rose to his feet to complete his second hundred with a four off Lungi Ngidi before retiring.

All-rounder Cameron Green (six) became the second batsman to retire hurt after tea, having been hit on the index finger by Nortje.

With pace spearhead Mitchell Starc struggling with a sore middle finger on his bowling hand, Green's injury could leave Australia short-handed in attack.

South Africa, however, may take little heart from Australia's struggles, with their batsmen having failed to surpass 200 in recent Tests.