Rory McIlroy, Adam Scott near top

SYDNEY -- Two-time former champion Greg Chalmers took a one-stroke lead Friday at the Australian Open after a 5-under 66 while marquee attractions Rory McIlroy and Adam Scott weren't far behind on a tough day for scoring.

Defending champion McIlroy played in difficult afternoon conditions at The Australian Golf Club and he persevered for an up-and-down 69 to be in a group tied for second.

"I felt like I had an opportunity today to maybe shoot a good one and put a little bit of space between myself and the rest of the field, but it didn't really pan out that way," McIlroy said.

McIlroy only had only one par on the back nine -- the 10th. He birdied the ninth with about a 70-foot putt, but also plunked balls in the water on two holes for bogeys.

Chalmers had seven birdies in his second round to move to 5-under 137 after 36 holes.

"It seemed to move around a little bit and change direction," Chalmers said. "Sometimes you think you should be downwind and because you've turned in a certain direction you're actually into the wind. I think I changed clubs two or three times on shots."

Scott and American Jordan Spieth played together in calmer morning conditions and Spieth (72) was in a group tied for sixth, two behind. That group includedformer Australian amateur Geoff Drakeford, who is playing his first tournament as a professional.

"I think the greens were certainly testing us," Scott said, "getting to understand the slopes on the greens and especially around the edges. I've hit a lot of wedge shots that have been a little mis-struck and then spinning off the greens. I guess that's got to do with the pin positions as well. So getting it very close to the hole is not that easy. I think the greens have to be the defense because there is no rough."

Scott, who moved from potential cut to contention with a 66, was three strokes behind.

"Yesterday I got off to a bad start, and I didn't scramble well when I had to and it started to get away from me," Scott said. "Today a couple of good shots coming up 14 and I made an eagle and momentum is on your side."

After two rounds, there were only 16 players under par.

Spieth had to call for a rules official on the par-3 fourth hole when a marshal stood on his ball, but neglected to tell him when he got to the green.

Members of the gallery informed Spieth, and after he took a drop, the American fluffed his chip and missed his putt for par. On the way to the next hole, he flung his ball into a creek.

His round ended well with birdies on his last two holes, but that wasn't enough to make it a good day for Spieth.

"It was a struggle, big-time struggle," Spieth said. "I wasn't hitting it well. If I wasn't putting well I may have shot 45 on the back nine.

"I just didn't find the ball-striking until the last few holes and then was very fortunate to grab a few birdies. I was really looking at making 4s and getting in and regrouping for tomorrow. But instead I kept myself in the tournament."