Spaniard Jon Rahm fired the best 61 in his career – which included a hole in one – to load the WGC-Mexico championship standings, where Justin Thomas will take the lead with a hit in the last round.
Rahm had started the third round with 10 shots ahead of one under the Chapultepec Golf Club.
However, a sensational start saw the 25-year-old making birds on six of the seven opening holes, with an eight-bogey who saw him turn in a curve at 30.
The Spaniard regained momentum as he picked up three more shots heading to the last two holes and hit a superb ace on the 17th par-three of 158 yards, where his tee shot took a rebound before finding the hole to close a remarkable ride.
Rahm’s 61 was a field record at Chapultepec, the lowest round of his career on the European Tour and the lowest joint round in the history of the World Golf Championships.
Rahm, the reigning champion of Race to Dubai, has four shots ahead, alongside the world number one Rory McIlroy and Bryson DeChambeau, who were the first after the second round.
Jon Rahm shot a third round of 61 in Mexico. Director of photography: Rob Carr / Getty
McIlroy signed for a three-under 68, bogeying on the sixth par-five and also the fourteenth, while DeChambeau – who had driven three to some point – got three of the final six holes to finish in a par 71 of level.
Meanwhile British Open champion Shane Lowry remains one down after a third even lap, interrupted by a double bogey on the 16th hole.
“I beat really good putts for the best part of a year, but they didn’t come in,” Rahm told the official European Tour website.
“From yesterday on my tenth hole they started to enter and today it went on.
“Basically I had tap-ins, tap-ins, tap-ins and 10 birdie feet and I thought” today could be a very special day. “
“So backing up with a great little bird at six and seven and one big tee shot out of eight, which is a difficult tee shot, I thought it could have been the day it ended.”
Rahm added: “I think a lot of us like to talk about how unfortunate we are sometimes and I think today was one of those days I was lucky.
“I hit the right shots, got the right rebounds and took advantage of it. There were a couple of holes where I could have been a little more unlucky
“I think we all compete and we want to win tournaments when everyone plays their best and if you win one of those fields on the stack, it’s a lot of fun and it’s a great result, so I hope to be in the lead tomorrow afternoon. “
Patrick Reed and South African Erik Van Rooyen both carded rounds of 67 to get involved to challenge world number four Thomas as well, who scored a third of six under the third round of 65 to sit 15 below.
Thomas made five little birds on the back nine, only to then release a cart in the 18.
He said: “I go out and play golf and keep doing what we’re doing. For the most part I feel like I’m playing well.”
British duo Tyrrell Hatton and Paul Casey are tied for seventh to 10 below after both rounds of 66 cards, while Chez Reavie made a hole in the first third of 167 yards.
World Golf Championships third round scores and totals – Championship of Mexico (USA, if not indicated, par 71):
198 Justin Thomas 67 66 65
199 Erik Van Rooyen (Rsa) 70 62 67, Patrick Reed 69 63 67
202 Rory McIlroy (Irl) 65 69 68, Jon Rahm (Spa) 72 69 61, Bryson DeChambeau 68 63 71
203 Paul Casey (Eng) 69 68 66, Tyrrell Hatton (Eng) 69 68 66
204 Kevin Na 71 68 65, Hideki Matsuyama (Jpn) 69 64 71, Gary Woodland 70 69 65
207 Abraham Ancer (Mex) 70 70 67, Billy Horschel 68 71 68
208 Benjamin Hebert (Fra) 73 70 65
209 Zach Murray (Aus) 71 69 69, Carlos Ortiz (Mex) 75 68 66, Justin Harding (Rsa) 71 71 67, Matt Kuchar 75 67 67, Tommy Fleetwood (Eng) 70 69 70, Sebastian Munoz (Col) 71 66 72 , Rafael Cabrera-Bello (Spa) 71 71 67, Kevin Kisner 73 69 67, Lee Westwood (Eng) 69 70 70
210 Scottie Scheffler 73 70 67, Xander Schauffele 72 72 66, Adam Scott (Aus) 74 68 68, Bubba Watson 67 72 71, Zander Lombard (Rsa) 73 68 69, Corey Conners (Can) 68 70 72
211 Danny Willett (Eng) 73 68 70, Sungjae Im (Kor) 69 72 70, Lanto Griffin 72 69 70, Chez Reavie 71 73 67
212 Marc Leishman (Aus) 74 70 68, Shane Lowry (Irl) 72 69 71, Matthew Fitzpatrick (Eng) 72 70 70
213 Shaun Norris (Rsa) 75 68 70, Ryan Fox (Nzl) 72 68 73, Branden Grace (Rsa) 71 71 71, Matthias Schwab (Aut) 71 68 74
214 Dustin Johnson 76 71 67, Shugo Imahira (Jpn) 74 70 70, Brendon Todd 72 71 71, Christiaan Bezuidenhout (Rsa) 72 72 70, Robert Macintyre (Sco) 76 68 70, Collin Morikawa 72 70 72, Bernd Wiesberger (Aut) 70 76 68
215 Cameron Smith (Aus) 73 73 69, Louis Oosthuizen (Rsa) 68 71 76, Brandt Snedeker 76 69 70, Pablo Larrazabal (Spa) 71 74 70
216 Jason Kokrak 73 70 73, Sergio Garcia (Spa) 74 72 70, Byeong-Hun An (Kor) 75 69 72
217 Francesco Molinari (Ita) 72 74 71, Victor Perez (Fra) 81 70 66, Charles Howell III 75 74 68, Jordan Spieth 74 73 70
218 Kurt Kitayama 76 70 72
219 Jazz Janewattananond (Tha) 73 73 73, Lucas Herbert (Aus) 75 70 74 Webb Simpson 72 73 74
220 Lucas Glover 71 73 76, Jorge Campillo (Spa) 77 74 69
221 Mike Lorenzo-Vera (Fra) 76 73 72
222 Matt Wallace (Eng) 74 77 71, Scott Hend (Aus) 72 75 75
224 Marcus Kinhult (Swe) 75 74 75, Sung Kang (Kor) 76 76 72
225 Ryo Ishikawa (Jpn) 80 72 73, Graeme McDowell (Irl) 76 74 75
227 Tae Hee Lee (Kor) 80 73 74