What it means: Will Wilcox was the early leader, but he faded down the stretch and was surpassed by Steele, who nearly matched the course record with his first round of the new season. His closest pursuers include a veteran and an upstart rookie, while Thomas opened with a 66 to continue the momentum from a successful rookie campaign.
Round of the day: Steele started quickly, with birdies on seven of his first nine holes to make the turn in 29. He added two more birdies on his inward half, and while a par on the par-5 ninth left him short of the course record, it still put him in position for his first win since the 2011 Valero Texas Open.
Best of the rest: Vegas just missed out on earning a PGA Tour card earlier this month at the Web.com Tour Championship, and he is teeing it up this week on a sponsor exemption. The Venezuelan had six birdies in his first nine holes and added an eagle on the par-5 fifth to begin the season with an 8-under 64 as he looks for his second Tour victory.
Biggest disappointment: Brandt Snedeker had a spot in one of Thursday's marquee groups, but he failed to produce much en route to a 1-over 73. Snedeker made only one birdie against two bogeys, and at 1 over he trails Steele by 10 shots and is in danger of an early exit in Napa.
Main storyline heading into Friday: While Steele is comfortable in the pole position, he has plenty of big names still within reach. In addition to Thomas, who nearly made the Tour Championship last month, Rose (67) and Rory McIlroy (68) both got off to solid starts and positioned themselves well to contend over the final three rounds.
Shot of the day: Nick Watney authored the shot of the day, but it was nearly the shot of the year. Watney hit a fairway wood for his second shot on the 580-yard, par-5 18th hole that rattled off the flagstick and lipped out for a near-albatross. The ball rolled only two feet past, leading to an easy eagle for the veteran.
Quote of the day: "Kind of a basic 63." - Steele, whose lowest round last season was a 64.