Charlie Hoffman and Rico Hoy each shot even-par 63s to take the lead at The American Express at La Quinta Country Club in California.
Hoffman birdied five of his last seven holes on the Nicklaus tournament course, one of three used for the event, while Hoy birdied eight of the par fours in 10 holes.
Hoffman, who included two eagles in his round, is chasing his first PGA Tour win since 2016 after back problems in recent years.
“Three years ago, I wasn’t very healthy and I wasn’t a very good golfer,” Hoffman said.
“I feel good right now, as I say, I could wake up in the morning and feel completely different.
“When I’m healthy, the weather’s warm, I feel like I can beat anyone in the world. When it’s cold and my back doesn’t feel good, I don’t think I can beat anyone in the world.”
Hoy added: “For me, this is my second year on the tour, so I’m still kind of starstruck by a lot of those guys, Hoffman, Cantley, Ricky, and so on.
“It’s really cool for me to put my name out there and just follow them, so that’s all I’m trying to do.”
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The pair lead the leaderboard at 16th, one clear of Austria’s Sepp Straka, American Mark Hubbard, who both had 64s at Pete Dye, and compatriot Justin Lower.
Australia’s Jason Day and American JJ Spawn are further back, followed by a group at 13 that includes last week’s Sony Open winner Nick Taylor and Rickie Fowler, who was tied for 62nd on the Nicklaus Course.
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