Rookie Sepp Straka birdied the final three holes to post a bogey-free, 9-under-par 63 in the opening round of the Safeway Open on Thursday in Napa, Calif.
Straka, a 25-year-old who was born in Vienna but attended the University of Georgia, is making his first PGA Tour start after earning one victory on the Web.com Tour.
He leads PGA Tour rookie Chase Wright by one shot, with Phil Mickelson (65, including six consecutive birdies) and Alex Prugh, one of eight players tied at 66, trailing closely at Silverado Resort.
Two-time defending champion Brendan Steele is among 10 players at 67. Steve Stricker is the last player on the Tour to win an event three consecutive years, earning the title the John Deere Classic from 2009-11.
—Field Level Media