Daniel Summerhays capitalised on Jason Dufner's stunning capitulation to take a three-stroke lead after the third round of the Memorial Tournament.
Dufner was unable to stop the rot as he watched his five-shot advantage atop the leaderboard vanish following a five-over-par 77 on Saturday.
The four-time winner on the PGA Tour threatened to run away with the tournament after breaking the event's 36-hole record at Muirfield Village on Friday but he faded dramatically, holing six bogeys and a double-bogey.
Things did not go according to plan for Dufner from the outset following four consecutive bogeys, starting at the second hole.
And Summerhays pounced with a four-under-par 68 to take control heading into Sunday's final round.
Just aim at the blimp.-- PGA TOUR (@PGATOUR) June 3, 2017
Daniel Summerhays leads by 2. pic.twitter.com/BbyexEXZVR
Summerhays had five birdies and a bogey to be clear at 13 under through 54 holes - ahead of Matt Kuchar (67).
Bubba Watson (68) and Justin Thomas (69) are level with Dufner at nine under, while Rickie Fowler (72) is a shot further back.
Former world number one Jordan Spieth is six shots off the pace after his third-round 71.
Spieth dropped four positions following a mixed day, which included six birdies, three bogeys and a double-bogey.
Kevin Streelman (67) and Kevin Kisner (70) are also seven under.
Phil Mickelson posted a 72 to be four under, a shot ahead of Australian pair Jason Day (67) and Adam Scott (71).