Jon Rahm hit four consecutive birdies and two eagles as he soared to the top of the leaderboard at the Farmers Insurance Open.
The 24-year-old dropped a shot on the par-3 third but picked up shots on four of the final five holes of his round to card a 62 for 10-under and a one shot lead in San Diego.
England's Justin Rose is a shot behind after carding a clean round of 63, opening with an eagle on the par-5 10th.
Also tied for second is American Doug Ghim, who is playing for the first time at the tournament.
He picked up shots on five straight holes on the front nine and went bogey-eagle-par on the closing three.
Scot Russell Knox is one of 12 players tied for 15th on five-under, alongside reigning champion Jason Day from Australia.
Three shots behind that is Tiger Woods, one of a large group who went round in 70, while Ireland's Seamus Power had a torrid time at Torrey Pines, reaching the turn on three over and dropping another three shots on the way in to sit tied for 151 on four over.
