Brendan Steele was 6-under-par 64 to claim the lead after the opening round of the Zozo Championship, where he finished as runner up to local favourite Hideki Matsuyama in 2021.
"I love it here," Steele said after he followed a chip-in on 17 with a birdie on 18.
Steele climbed to the top of the leaderboard with four consecutive birdies to the end the round, helping erase a bogey on 14.
The steady rainfall Friday didn't slow down a large crowd or a huge push from Americans to the top of the leaderboard.
Steele playing partner Adam Schenk's bogey-free 65 was good for a solo spot in second place and one shot ahead of three tied at 66: Keegan Bradley, Matthew NeSmith and Sam Ryder.
Matsuyama was 1-over (71) and tied for 41st after 18 holes. 2020 Tokyo Olympic Games gold medalist Xander Schauffele (T6) opened with a 3-under 67 in his season debut. Rickie Fowler and Maverick McNealy are tied with Schauffele, Chilean Mito Pereira and Japan's Kazuki Higa.
"It was raining and it was a tough round – I didn't give a good account of myself today," said Matsuyama, who had three bogeys and two birdies.
Fowler had seven birdies but a double-bogey on 11 spoiled his shot at the lead and a more pristine scorecard.
Steele's last win on tour was the 2017 Fortinet Championship, one of his three PGA Tour tournament wins.
Thursday's first round was Steele's best opening round since the 2016 Valero Open, where he finished tied for 13th. This is the seventh time Steele has led a tournament through the opening 18.