Dustin Johnson will take a four shot lead into the final round of the WGC-Mexico Championship as he seeks a sixth World Golf Championships title at Chapultepec Golf Club.
The American is the only player to have won all four WGC crowns and has won this one twice in 2015 and 2017 - the first year it was played in Mexico City.
He led by six after eight holes in round three but had to recover from a double-bogey on the tenth to post a 66 that moved him to 16 under, four clear of Rory McIlroy.
Americans Patrick Cantlay and Patrick Reed, Spaniard Sergio Garcia and Australian Cameron Smith were then seven shots off the lead as Sunday looked set to be a two-horse race between a pair of World Number Ones with five Major Championships between them.
"It's there to attack for sure," said McIlroy. "Obviously four shots behind DJ is going to be a tall order to overcome but I was happy with how I played the last ten holes.
"I need to get off to a better start tomorrow than I did today and if I can do that hopefully I'll be right back in the tournament."
Saudi International powered by SBIA champion Johnson had gone 57 holes without a bogey at Chapultepec before the double on the tenth that remains his only blemish this week.
"You're always pleased when you've got a nice lead going into Sunday," he said.
I feel like the game is in really good form so it should be a lot of fun - Dustin Johnson
"I'm going to have to go out and play really well if I want to win tomorrow. I feel like the game is in really good form so it should be a lot of fun."
McIlroy went a long way right off the first tee, finding sand with his second for a bogey, and while he went right again off the second tee he got up and down from a fortunate lie to bounce back.
That left him four behind Johnson, however, as the 34-year-old drove the green to leave himself four feet for an eagle.
McIlroy's bounceback continued as he made a 20-footer from the fringe at the par three third to get back into double figures but an approach to eight feet on the fifth restored Johnson's four shot lead.
A three putt from McIlroy on the seventh and a poor tee-shot on the next had Johnson six clear but the Northern Irishman clawed a shot back at the turn, holing from 34 feet after hitting the pin.
Johnson's bogey free run was then shattered as he was lucky not to go out of bounds off the tee, hit a tree with his second, hit another tree after being handed a free drop from the sprinkler cables and eventually signed for a double-bogey.
McIlroy's approach to four feet meant there was a three shot swing on the tenth and after both men birdied the par five 11th, Johnson holed from seven feet at the 12th before McIlroy three-putted the 14th to put Johnson four ahead again.
A brilliant second from McIlroy to 12 feet and a stunning greenside chip from Johnson set up a pair of birdies on the par five 15th, and McIlroy made another on the next from 11 feet but Johnson hit back from 17 feet on the 17th.
It's there to attack for sure - Rory McIlroy
Masters Champion Reed matched the lowest round of the day with a birdie-birdie-birdie finish in a 64 that also featured two eagles - including a chip-in on the par four second.
Garcia placed the Green Jacket on Reed's shoulders last spring and he signed for a 69, while back-to-back Australian PGA Championship winner Smith carded a 68.
The highlight of Cantlay's 65 came when he almost made a hole-in-one on the par four 12th, driving the green - much to the surprise of the putting Kevin Kisner - and tapping home from three feet for an eagle.
Thai Kiradech Aphibarnrat and England's Ian Poulter were at eight under, two shots clear of Tommy Fleetwood, David Lipsky, Louis Oosthuizen and Tiger Woods.
