Derek Fathauer will take a one-shot lead into the final round of the OHL Classic at Mayakoba after replacing Graeme McDowell at the top of the leaderboard on Saturday.
American Fathauer carded a five-under-par third round of 66 at El Camaleon Golf Club to reach 16-under for the PGA Tour event in Playa del Carmen, Mexico.
The 29-year-old, whose only career triumph to date remains the 2014 Web.com Tour Championship, sank four birdies on the front nine and one on the way back to turn in a bogey-free card.
"I've just got to have fun, play golf, play my game, and whatever happens will happen," Fathauer said of his chances.
He leads by one shot ahead of fellow American Jason Bohn, who shot 65 to reach 15-under.
Northern Irishman McDowell, having led by one shot after the second round on Friday, is now one of four players tied for third at 13-under. The 2010 US Open winner got off to a bad start with a double-bogey six at the first and made two more bogeys for the day.
The 36-year-old fought back admirably with five birdies in total to record a one-under 70 and stay firmly in contention going into the final round on Sunday.
Americans Harold Varner III and Justin Leonard join McDowell on 13-under, together with Scotsman Russell Knox, who shot up the leaderboard courtesy of a six-under 65.
Swede Freddie Jacobsen fared even better, producing an eight-under 63 to join five other players in a share of eighth at 11 under, behind Johnson Wagner in outright seventh.