Overnight leader Adam Scott battled through the Sydney wind and rain for a mixed bag of a round of two-under-par 70 to take a two-stroke lead over Rory McIlroy at the halfway stage of the Australian Open on Friday.

McIlroy, growing in confidence by the round, benefited from easier early conditions to post a nine-birdie 65 and join the world number two at the top of the leader board on 10-under before the Australian had even teed off.

The U.S. Masters champion lit up the Royal Sydney Golf Club with a course record 10-under 62 in bright sunshine on Thursday and initially continued in the same vein by picking up shots at two of his first three holes.

The stiffening wind and driving rain took their toll, though, and five further birdies, three bogeys and one double bogey later, Scott was signing for his second round with the same two-shot cushion.

"It was a tough afternoon, plenty of good stuff in there but made a few mistakes in the tricky conditions," Scott told reporters.

"At times, it was extremely difficult and I think I held it together pretty well.

"It was going to be a day for hanging in. I made lots of birdies but bogeys were easy to come by if you were just slightly off and probably most scorecards would have looked similar this afternoon."

World number six McIlroy's growing confidence at the tail-end of a difficult season was clearly evident in his second round at the Royal Sydney, where he tightened up the putting that had left him seven shots behind Scott overnight.

"As seven-unders go, I think it was a pretty comfortable one. I don't think I did anything really spectacular out there," the Northern Irishman said.

GREEN ACE

"It feels good, I played well, putted much better today than I did yesterday too, so that was a big positive. I'm in a great position going into the weekend."

If McIlroy's snaking 14-footer for a birdie at the sixth was the putt of the day, Richard Green took the iron shot honors for his hole-in-one at the same par-three.

The 42-year-old Australian also hit six birdies with two bogeys in his early round of 66 to claim third place a shot behind McIlroy, but there was no doubting the highlight of his day.

"I think it was about 157 yards or something like that, which was I suppose just with the conditions, there's a little bit of wind off the left and it suited the draw in there and just got it, perfect," the European Tour regular said.

Matt Jones was a shot further back in fourth on eight-under after a second 68 and will play with his compatriot Green in Saturday's third round.

With all due respect to the pair, most eyes will probably be on the group teeing off behind them and tournament organizers will be hoping for a hotly contested duel between the best two players in the field.

Scott has won the Australian PGA and Masters in the last month and could hardly be in better form.

Despite McIlroy's poor season, though, he was certainly not writing off the former world number one and twice major champion.

"Obviously he's one of the best players in the world so I'm going to have to bring my best game and try and match it with him," Scott said.