Japan's Hideki Matsuyama has set the pace on the opening day of the Olympics, carding an impressive bogey-free eight-under 63. (More Sports News)
On a day interrupted by threats of lightning that saw play suspended multiple times, Xander Schauffele had the chance to close in on the lead, but instead finished two strokes behind him on 65.
And it gets tight behind him on the leaderboard in a three-way tie for third between Chile's Joaquin Niemann, Argentina's Emiliano Grillo and South Korea's Tom Kim after rounds of 66.
After solid opening rounds, world number one Scottie Scheffler, Tommy Fleetwood and Jon Rahm were among the nine tied for sixth on four-under.
Meanwhile, it was an up-and-down day for Rory McIlroy, who finished one stroke further back in joint-15th after he carded five birdies and an eagle as well as four bogeys to card a three-under 68.
His Ireland team-mate Shane Lowry finished on an even 72, sitting in tied-47th.
