Adam Scott made a solid start to the defence of his Australian Masters title after opening with a four-under 67 in damp and blustery conditions at Royal Melbourne.
The Masters champion lies two shots behind surprise leader Nick Cullen, who carded an eagle and six birdies in a sparkling 65.
Scott, surrounded by huge galleries, started at the 10th and picked up an early birdie at 13 before reeling off six straight pars.
The 33-year-old then stormed into the outright lead with four consecutive birdies from the first, but his ball striking let him down over the closing holes and he blotted his card with a bogey at eight.
Scott signed off with a par before heading straight to the practice area, although he admitted afterwards that he was generally satisfied with his performance.
"I think 67 around here is a good score," said the world No 2, who cruised to the Australian PGA title last week.
"I felt like I left a couple out there but my game is in pretty good shape and four rounds like that might go a long way this week."
Scott's opener earned him a share of the clubhouse lead with German Maximilian Kieffer, but both were upstaged by the unheralded Cullen.
The Adelaide professional, whose brother Dan played Test cricket for Australia, leapt into contention when he chipped in for eagle at the 11th before rolling in birdie putts at 12, 13 and 17.
The 29-year-old took the gloss off an excellent day with a bogey at the last, but he said afterwards: "I think it's an amazing golf course and I'm really loving it here this week.
"Any time you can shoot 65 on a course like this you have to be happy."
American Ryder Cup star Matt Kuchar laboured to a level-par 72, while Jarrod Lyle returned to action for the first time since March 2012 after undergoing treatment for leukemia.
The popular Australian, a regular on the PGA Tour, understandably struggled to keep his emotions in check on the first tee and mixed three birdies with four bogeys in a creditable 73.
"It was a feeling I thought I would never experience again," Lyle said. "The emotions overtook me on the first tee.
"It's something I always dreamed of, having my daughter at a tournament. It was great she got to see what I do."