Chez Reavie shot an eight-under 63 to take a one-shot lead after the opening round of the AT&T Pebble Beach Pro-Am in California.
Reavie eagled the 16th hole at Monterey Peninsula - the easiest of the three courses in use for the tournament - to sit one shot ahead of Freddie Jacobson, Cameron Smith and Bronson Burgoon.
"Even on days I putt well, I still don't make as many putts as I made today," Reavie told reporters.
Jacobson made five birdies in a six-hole run at Pebble Beach, while Australia's Smith and America's Burgoon carded 64's at Monterey Peninsula.
Justin Rose - who was playing alongside Justin Timberlake - is among seven players one shot further back on six under after ending his round by sinking a 50-foot birdie putt at Spyglass Hill.
Rose said: "I heard some strange reports about Spyglass, like the first few holes are great, then it disappears into the hills and it's not that good. That's not what I saw. That's a pretty stellar golf course to me and really enjoyed playing it."
World number one Jordan Spieth failed to get up-and-down for birdies on the par fives three times at Spyglass Hill as he opened with a 71, as did US PGA champion Jason Day.
Spieth said: "I played the hardest holes on this golf course four-under par, and then I played all the easy ones over par. I just was not quite dialed in with the wedges or short game.
"But all in all, to actually shoot one1 under with what I felt like I should have shot today is promising, considering we're going to the two easier courses in my mind."