Phil Mickelson kicked off the new PGA Tour season with a scorching 7-under 65 to sit two shots back after Round 1 of the Safeway Open on Thursday.
Lefty strung together six consecutive birdies during his bogey-free round, including a monster 46-foot putt on No. 13.
"Today was kind of an anomaly," Mickelson said after his round, according to Ryan Lavner of Golf Channel. "Don't let the one good round fool you."
Mickelson also admitted he had one of his worst warmups in a long time prior to his first round, hitting both sides of the boundary fence on the range.
On Wednesday, the American Ryder Cup team member told Golf Channel he was "absolutely exhausted" after flying straight from Paris, France to Napa California - the only player to do so.
He went 0-2 in competition at last week's Ryder Cup, conceding the winning point to Francesco Molinari after hitting his tee shot into the water.
Mickelson is two shots back of leader and PGA Tour rookie Sepp Straka, who both opened his career with a 9-under 63. Another rookie, Chase Wright, is at 8-under.
Former Major League Baseball pitcher Mark Mulder shot 3-over after receiving a sponsor's exemption into the tournament.