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.

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

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.

Scott and American Jordan Spieth played together in calmer morning conditions and Spieth (72) was in a group tied for sixth, two behind. Scott moved from potential cut to contention with a 66.

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