Harris English used a red-hot start to equal his career-low round of 62 and seize a two-stroke lead after Thursday's opening round of the WGC St. Jude Invitational.
English stormed out of the gate with six birdies in his first seven holes and closed by making birdie on three of his last four to finish on eight-under in the $10.5 million event at Memphis, Tennessee.
England's Ian Poulter, Mexico's Carlos Ortiz and Americans Matthew Wolff and Jim Herman shared second at six-under 64.
Bryson DeChambeau, fellow American Scottie Scheffler and Australian Marc Leishman share sixth after shooting 65s at the TPC Southwind course.
The 32-year-old English said he wasn't thinking of shooting a 59 but rather trying to focus on one hole at a time.
"I'm just trying to stick to my strategy every hole," he said. "I didn't get too far ahead of myself because I know this course can come up and bite you at any moment.
"You start hitting in the rough, you start missing greens, it can get tough. I was just happy with the way I fought back."
Several players came to Memphis from Tokyo after the final round of the men's Olympic golf tournament, which wrapped up Sunday.
Top-ranked Jon Rahm is not in the field after testing positive for Covid-19. He and DeChambeau were forced to withdraw from the Olympics. DeChambeau was allowed to play this week after passing the event's testing protocols.
English, who was third at the US Open, has won two tournaments this season, including the Travelers Championship in June, where he outlasted Kramer Hickok in an eight hole playoff. He also won the PGA Tournament of Champions in January.
He opened his round with four straight birdies and made the turn in seven-under 28. He had two bogeys in a three hole stretch in the middle of the round but got back on track with a sizzling finish.
"Had two bogeys on 10 and 12, but climbed back in it, and birdieing the last three out of four is a great way of finishing it off," he said.
This is world number seven DeChambeau's first tournament since testing positive for the coronavirus after declining to get the vaccine.
"Made some birdies, which is nice," said DeChambeau. "It's a tough golf course for me with the way I play, so very excited for that."
At the Open Championship in July, DeChambeau was scolded by his equipment sponsor for blaming his poor play on their product. He has also been embroiled in a lengthy ongoing feud with fellow golfer Brooks Koepka.
"I'm looking forward to the rest of the weekend," he said. "I feel like I can be there to win on Sunday."
Open champion Collin Morikawa and defending tournament champ Justin Thomas shot 67s.
Northern Ireland's Rory McIlroy got off to a disappointing start with a two over 72 for a share of 62nd place.