The American can become the first player to win the US Open on his debut in the major since amateur Francis Ouimet in 1913 and the first professional to achieve the feat.
He would also be the youngest US Open champion since the legendary Bobby Jones in 1923 and match the achievement of Jordan Spieth, who claimed the coveted crown as a 21-year-old in 2015.
“It’s really early in my career, but I feel like I have the game to win,” Wolff said. “I feel like I’m ready to win out here and win a major.”
Wolff, already a winner on the PGA Tour last year in his first season, started the day four shots adrift of the leader Patrick Reed but by reaching the halfway point of his round in just 30 shots — five-under-par — he was making a major statement of intent.
He shared the lead at that point with Reed, who went to his turn in 34, but the 2018 Masters champion fell away disastrously on the back nine, ending with a 77 after a string of bogeys and a double bogey to finish the day at three-over-par.
Reed’s playing partner Bryson DeChambeau emerged as the biggest threat to Wolff’s lead, with birdies at the 16th and 17th leaving him just one adrift of Wolff, only to undo that good work with a finishing bogey for a level-par 70.
Big-hitting DeChambeau is also seeking his first major and like Wolff finished tied for fourth at Harding Park in San Francisco in the opening major of a truncated season.
“The past two majors I’ve played in I’ve been right in contention,” he said after his round.
“It’s definitely validating, albeit there’s a lot more to go. I’ve got to figure out a lot more. I am excited to be in this position for sure. There’s no better place to be,” he added.
Former British Open champion Louis Oosthuizen of South Africa is two shots further back with Hideki Matsuyama of Japan and two Americans, Xander Schauffele and Harris English, in the group at level par, five adrift of the lead.
A strong challenge could also come from Northern Ireland’s Rory McIlroy, one of only six players to break par in another difficult day on the famed Winged Foot course.
His two-under 68 left him on 211 — one-over-par — and with he believes a realistic chance of adding to his tally of four majors.
“If I’m within six going into tomorrow that’s not a lot on this golf course. I feel like I’m right in it,” he said.
They will all be shooting for Wolff, like Morikawa a product of the Southern Californian golf scene, but who has an added incentive to lift the trophy.
Wolff revealed after this round that his agent was battling stomach cancer, having been recently diagnosed.
“I’ve been thinking about him a lot out there. He doesn’t want anyone to feel bad for him, but like I said, it just puts things in perspective,” said Wolff.
“And I’m going to go out there, try to make him proud and go have a good time,” he added.