Defending champion Brendan Steele fired a seven-under 65 to share the lead after the opening round of the Safeway Open.
The American, who claimed his second and most recent PGA Tour win in Napa, California last year, mixed six birdies with an eagle and a bogey on Thursday.
Steele is joined by countrymen Tyler Duncan and Tom Hoge atop the leaderboard after the first round at the Silverado Country Club.
At the opening event of the 2017-18 season, Steele started on the back nine and made five birdies in six holes.
He climbed into seven under through 14 when he put an approach to within three feet for eagle at the par-five fifth hole.
Steele's only blemish followed, at the sixth, before he finished with a birdie and the 34-year-old sits alongside Duncan and Hoge.
Lucas Glover, Chez Reavie, Jamie Lovemark and Argentine 2015 champion Emiliano Grillo carded 67s to be tied for fourth.
A shot behind them are Zach Johnson, Kevin Tway, Ryan Moore and Maverick McNealy, the latter a 21-year-old on his professional debut.
Phil Mickelson also made a decent start, shooting a three-under 69 to be tied for 12th.