Bryson DeChambeau moved to the top of the Memorial Tournament leaderboard by one stroke after the penultimate round, while Tiger Woods elevated himself back into contention.
DeChambeau carded a six-under-par 66 in the third round to take the lead at Muirfield Village Golf Club on Saturday.
The American birdied four of his last six holes during a bogey-free round to be 14 under heading into Sunday's finale.
With four top-five finishes already this year, DeChambeau is trying to etch his name into Ryder Cup contention as captain Jim Furyk looks to build his team in France.
Patrick Cantlay (66), and overnight leaders Kyle Stanley (70) and Joaquin Niemann (70) all finished the day tied for second at 13 under.
An Byeong-hun is lurking at 12 under following a three-under 69, two shots better off than Fort Worth Invitational champion Justin Rose (69).
Former world number one Woods and four-time major winner Rory McIlroy made a charge up the leaderboard on moving day.
Woods reached 11 under before two late bogeys dropped him back to nine under for the PGA Tour tournament, having signed off for a third-round 68.
The 14-time major champion was tied for the lead at one stage but dropped shots at 16 and 18 halted Woods' momentum.
Northern Irish star McIlroy, who made the cut on the mark, shot an eight-under 64 to get back in the mix.
After opening the event with rounds of 74 and 70, McIlroy was flawless on Saturday as he recorded an eagle and six birdies to rise to 11th, a shot behind Woods.
Adam Scott, still unqualified for the U.S. Open, registered a two-under 70 to join McIlroy at eight under.
World number one Justin Thomas (68) and Rickie Fowler (68) ended the round seven under through 54 holes, while Dustin Johnson's 72 saw him close out the day a stroke adrift.