Bryson DeChambeau moved to the top of the leaderboard following a flawless third round at the Memorial Tournament in Ohio.
Looking for his second PGA Tour title after winning last year's John Deere Classic, Californian DeChambeau claimed a score of 66 on Saturday, thanks to six birdies, to hold a one-shot lead over a trio not far behind.
Patrick Cantlay, who also carded 66 on the third day, played a very different round to his compatriot, with four birdies, two eagles and two bogeys to sit joint second.
Also in a three-way tie for second are midway leaders Joaquin Niemann and Kyle Stanley after both players ended the day with scores of 70.
Nineteen-year-old Chilean Niemann, who had shared the top spot after day one, had a mixed third round with bogeys on the 10th, 15th and third holes cancelling out three birdies as an eagle on the seventh saw him reach two-under for the day.
Stanley joined Niemann and Cantlay on 13 under ahead of Sunday's final round thanks to six birdies and four bogeys.
South Korea's Byeong Hun An sits a shot further behind after a flawless 69, picking up birdies on the 13th, 15th and seventh for fifth, while England's Justin Rose is two shots further back in sixth - also carding 69 but with three bogeys on the back nine along with six birdies.
Tiger Woods is just one place further back in a four-way tie for seventh, with Northern Irishman Rory McIlroy six shots off the lead in a tie for 11th after a poor opening round 74.
He recovered with a flawless 64 which included six birdies and an eagle on the fifth for the best round of the day.