San Francisco - Defending champion Brendan Steele ripped up the back nine en route to a seven-under 65 to take a share of the lead after the first round of the USPGA Tour's Safeway Open on Thursday.
Steele was tied with fellow Americans Tom Hoge and Tyler Duncan heading into the second round of the Tour's season-opening event for 2017-18 at the Silverado Resort and Spa.
Steele, who has two wins on the Tour, recorded five birdies in a six-hole stretch from number 13 to number 18.
He added an eagle on the fifth but followed with a bogey on the next hole.
"A little bit of everything worked for me today," Steele said. "I had a really good ball-striking day. I don't think I missed a green, so that really helps. And then I had a good putting day as well, so you put that together and it's going to be pretty good."
Chez Reavie, Lucas Glover, Jamie Lovemark and Argentina's Emiliano Grillo are tied for fourth at 67.
Zach Johnson, Kevin Tway, Ryan Moore and Maverick McNealy share eighth place at 68.
Hoge's hot round came three days after he earned his PGA Tour playing card for the season by climbing into the top 25 of the Web.com Tour at that circuit's season finale.
Beginning his Thursday round on the back nine, the 28-year-old Hoge made birdies at 11 and 12, sandwiched two pars around a birdie at the 14th, then added birdies at holes 16, 17 and 18 to make the turn in 6-under 30. He carded one more birdie at number six to cap his bogey-free round.
"I played really well the whole day," Hoge said. "I was in a lot of the fairways, a lot of greens and then made a few putts. I just took advantage of some opportunities.
"I feel like I've been playing pretty well. So it was nice to get going right away here in Napa and keep the momentum going."
Duncan's round was highlighted by an eagle at the 10th.
Phil Mickelson shot a 69 and was one of 12 players tied for 12th.
Leading first-round scores on Thursday in the US PGA Tour Safeway Open at Napa, California (USA unless noted):
65 - Brendan Steele, Tyler Duncan, Tom Hoge
67 - Lucas Glover, Chez Reavie, Jamie Lovemark, Emiliano Grillo (ARG)
68 - Zach Johnson, Kevin Tway, Ryan Moore, Maverick McNealy
69 - Graham DeLaet (CAN), Zac Blair, Brian Stuard, Bud Cauley, Webb Simpson, Phil Mickelson, Scott Brown, Harold Varner, Kevin Streelman, Conrad Shindler, Joel Dahmen, Zhang Xinjun (CHN)