|WGC Mexico Championship, third-round leaderboard:|
|-12 J Thomas (US); -11 D Johnson (US); -10 R McIlroy (NI), P Mickelson (US); -9 L Westwood (Eng), J Rahm (US); -8 T Fleetwood (Eng), T Hatton (Eng), T Pieters (Bel)|
|Selected others: -7 J Spieth (US); -6 R Fisher (Eng); -5 A Sullivan (Eng); Level J Rose (Eng)|
|Full leaderboard (external site)|
American Justin Thomas made a hole-in-one at the 13th on his way to taking the lead from world number one Dustin Johnson in round three of the World Golf Championships event in Mexico.
Thomas, 23, watched as his ball bounced once and flew into the hole on 13, helping him to a round of 66.
He leads on 12 under, one clear of Johnson (66) and two ahead of Rory McIlroy (70) and Phil Mickelson (68).
Jordan Spieth of the US made a bogey-free 63 to move to seven under par.
Johnson led for much of the day as overnight leader McIlroy failed to fire, but after five birdies the American slipped back with a bogey on 16, allowing Thomas to go past him.
Thomas came through the back nine in 31 shots, adding birdies at the 15th and 16th to ensure he will go out last alongside Johnson on the final day.
Mickelson finished the day on 10 under par after an extraordinary back nine, which saw him require three free drops in succession after a spectator picked up his ball on the 10th, and he then drove into the bushes on 11 and 12.
Playing partner McIlroy remained very much in contention after a back nine that produced one birdie and eight pars.
"It was hard to get any rhythm because Phil was here, there and everywhere, so I was waiting a lot," McIlroy said after his one-under-par round.
"It probably shouldn't have affected me but it did a little bit."
England's Westwood moved within a shot of the Northern Irishman thanks to a 66, while compatriots Tommy Fleetwood (66) and Tyrrell Hatton (68) are one further back on eight under.
McIlroy will return to world number one if he wins in Mexico and Johnson finishes worse than fourth on his own.