Los Angeles - World number one Jon Rahm fired a course record-equalling 12-under par 61 to grab a share of the third-round lead alongside Cameron Smith in the US PGA Tour Tournament of Champions on Saturday.
Rahm, who started the day three behind Smith, matched the course record set just hours earlier by Justin Thomas on the par-73 Plantation Course at Kapalua in Hawaii.
He finally caught Australia's Smith on the final hole, Smith posting a nine-under par 64 as the leading duo finished 54-holes on 26-under 193.
They were five shots in front of American Daniel Berger, who closed with five straight birdies in a seven-under 66 for 198.
"It was pretty remarkable," Spain's Rahm said of a round that saw him at even par through four holes and 12-under through the remaining 14. That included a run of five straight birdies from the seventh through the 11th.
He blasted out of a greenside bunker to four feet to birdie 14, the stuck his approach at the par-five 15th four feet from the pin for eagle, then roared home with three more birdies.
"It was really fun when Cam is doing pretty much the same thing," Rahm said of the fireworks in the final group. "We were going back and forth."
Smith opened with four pars before the first of his nine birdies at the fifth.
He birdied three in a row from the ninth through the 11th -- where he rolled in a 20-footer and also birdied from a greenside bunker at 14 to launch a run of four straight birdies.
After Rahm rolled in a 16-footer at 16 to briefly pull level, Smith made his six-footer at the same hole to keep his lead at one shot.
At the 17th, Rahm drained a 29-foot birdie only for Smith to answer again with a 28-footer of his own.
But Smith couldn't capitalize on the par-five 18th, where Rahm made an eight-foot birdie putt to seize a share of the lead in the elite event for last season's tournament winners.
"That was some really good golf from both of us," Smith said.
Just hours earlier world number eight Thomas has charged up the leaderboard with his 61, breaking the record set in 2003 by South Korean KJ Choi and since matched by four players.
"I played well. Didn't do anything crazy. Just took advantage of all the, I felt like, easy opportunities and chances that I had and hit a lot of really good drives, quality iron shots, and wedges," Thomas said.
"If there’s such a thing as an easy 12-under, I definitely felt like it was," added Thomas, who had followed up a one-over opening round with a six-under effort on Friday.
He got going with a 14-foot birdie at the third hole, birdied the fourth then rolled in a 43-foot eagle at the par-five fifth.
After a birdie at the ninth he blitzed the back nine with birdies at 12, 13 and 14, an eagle at the 15th and another birdie at 16, finally capping his round with a birdie at 18.
Thomas was two off the lead when he walked off the course, but nine adrift when the round ended.
Australian Matt Jones fired a 62 to head a group sharing fourth on 199 alongside South Korean Im Sung-jae (65) and American Patrick Cantlay (66).
In the ideal conditions, Rahm said, he and Smith would have to "keep it full throttle" on Sunday.
"Assuming conditions are the same again we're going to need a low round," Rahm said.