Hayden made a determined 111 while Gilchrist finished the day unbeaten on 94 when bad light ended play five overs early at the Sydney Cricket Ground.

Hayden and Gilchrist also shared a 97-run partnership for the fifth wicket as the world champions recovered from a mid-order slump to pile on the runs against a World XI still licking their wounds from last week's 3-0 loss in the one-day series.

"I think everyone who had the ball really worked hard today, I don't think the pitch provided a lot for anyone," World XI captain Graeme Smith said.

"But if we can defend 400 tomorrow and hopefully bat well, then that's a good position in the game and we can really attack in the second innings.

"I think it's going to be slow for three days and then take some turn. The first innings will become crucial."

The world selection had made the perfect start when Steve Harmison clean bowled opener Justin Langer for a duck from the third ball of match and his England team mate Andrew Flintoff captured the prize wicket of Australia captain Ricky Ponting for 46.

Luck also seemed to be going their way as three Australians, Michael Clarke, Simon Katich and Shane Watson, were all given out by the video umpire as part of an experiment into the increased use of technology.

Clarke left the playing arena shaking his head in disbelief after being adjudged to have been caught bat-pad for 39, Katich was run out for a duck and Watson was trapped leg before wicket to Sri Lankan off-spinner Muttiah Muralitharan for 24.

Their dismissals threatened to ruin Australia's hopes, on the day John Buchanan was reappointed their coach for another two years, of building a big total on a placid pitch offering little encouragement to either pace or spin.

Muralitharan was the pick of the World XI bowlers, capturing two wickets from 30 overs, while Harmison, Flintoff and New Zealand spinner Daniel Vettori collected one apiece.

Hayden, whose international career was in jeopardy before he scored a century in the last Ashes test, repaid the selectors for their faith with his 22nd Test hundred.

The broad-shouldered Queens-lander began cautiously, scoring just 28 in the morning session, before accelerating after lunch.

"I'm not trying to hoodwink myself, I'm a naturally aggressive player and if the bowling's off then that's what I'm trying to do," he told a news conference. "But if the bowling's on I guess there's no point in taking the option of going hard."

Hayden twice got the benefit of the doubt to loud lbw appeals, including one which was referred to the video umpire, before reaching his hundred after tea off 161 balls when he drove Harmison to the boundary. He was dismissed after tea for 111, caught by Jacques Kallis off Muralitharan.

Gilchrist, player of the series in last week's three one-dayers in Melbourne, was in a far more aggressive mood.

He smashed eight boundaries and four sixes off only 109 balls to reach the close just six runs away from his hundred with Shane Warne on one.

Ponting had also looked to be in great touch as he got within sight of a half-century before an uncharacteristic error brought him undone just before lunch.

Harmison, overlooked for the one-day series, sent Langer tumbling to the pitch with his second delivery and then knocked his off-stump out of the ground with the next ball.

Ponting struck six boundaries and a six and looked to be on his way to a bigger score when he tried to glance a ball from Flintoff through the vacant gully area only to misjudge the angle and be caught by a diving Kallis at second slip.