Second Test, Durban (day three, close):
Australia 352 & 292-3 v South Africa 138-9
Dates: 6-10 March Start time: 0830 GMT
Coverage: Scorecard and reports on BBC Sport website. Live on Sky Sports
Hughes scored 115 in Australia's first innings in Durban
Phillip Hughes became the youngest player in Test history to score two centuries in the same match as Australia piled on the runs in Durban.
The 20-year-old was unbeaten on 136 as his side reached 292-3, a lead of 506.
Captain Ricky Ponting hit a speedy 81 in a 164-run second-wicket partnership with Hughes and in doing so became the fourth highest run scorer in the game.
The last two South African wickets fell in the day's first three balls with no addition to their overnight 138-7.
Peter Siddle had Dale Steyn caught behind off the second ball of the morning before trapping Makhaya Ntini leg before for a golden duck to leave JP Duminy stranded on 73.
Their total of 138-9 (opener Graeme Smith retired hurt after breaking a bone is his right hand on day two) left them 214 adrift of Australia's first innings total but the visitors opted not to enforce the follow-on.
Hughes and Simon Katich set about the South African attack with some gusto and raced to an opening half-century stand in just 66 balls.
But Katich was caught in the gully by Paul Harris off Jacques Kallis for 30 as he attempted a delicate feather down to third man.
Ponting and Hughes both reached their half centuries before tea and the captain lifted Steyn over midwicket for four to overtake fellow Australian Steve Waugh's total of 10,927 Test runs to move to number four on the highest run scorers list.
LEADING TEST RUN SCORERS
Sachin Tendulkar, Ind - 12,429 runs, 156 Tests
Brian Lara, WI - 11,953 runs, 131 Tests
Allan Border, Aus - 11,174 runs, 156 tests
Ricky Ponting, Aus - 10,948 runs, 130 Tests
He fell 19 runs short of his century though when he hooked Morne Morkel straight to Neil McKenzie at deep square leg to leave Australia 219-2.
Hughes, who had hurried to his half century in 78 deliveries, took another 169 to score the next 50.
He was particularly careful against spinner Paul Harris who bowled a defensive line into the rough outside the left-hander's off-stump.
But he retained his composure and, after spending 24 deliveries in the 90s, cut a wide Morkel ball to the boundary to bring up his century and break George Headley's record.
The West Indian was 169 days older than Hughes when he set the twin-century record against England at Georgetown in their 1929/30 series.
It was a remarkable effort by Hughes who will have done his chances of becoming Matthew Hayden's long-term successor at the top of the Australian batting order no harm at all.
"It's a very special moment," said Hughes.
"I had to grind it out and I was determined not to give it away after I got a start.
"I knew if I just kept going and batting there was a big one for the taking.
"It's something I'll never forget and I'm just really excited."
Kallis took a sharp low chance at slip to remove Mike Hussey who had scored 19 before being undone by a turning delivery from Duminy.
Michael Clarke and Hughes took Australia to the close without further mishap as the tourists built up a lead of 506 with two days remaining.