Dustin Johnson remains in pole position to claim a sixth World Golf Championship title after taking a four-stroke lead into the final round of the WGC-Mexico Championship.
The world No 3 recovered from a mid-round double-bogey to post a five-under 66 at Chapultepec Golf Club on Saturday and double his advantage over overnight challenger Rory McIlroy.
McIlroy mixed seven birdies with four bogeys to shoot a third-round 68 playing alongside Johnson, with former Masters champions Patrick Reed and Sergio Garcia a further three strokes back in the group tied for third.
Going out in the final group, McIlroy failed to get up-and-down from the sand to save par at the first but drained a 15-foot birdie at the next, where Johnson superbly drove the par-four green to set up a close-range eagle.
The Northern Irishman rolled in a 20-footer from the fringe at the par-three next to move back within two, only for Johnson to hole from eight feet at the fifth and go three clear.
McIlroy three-putted the seventh and dropped another shot at the eighth to briefly double Johnson's advantage to six, although responded by nailing a 35-foot birdie at the next to turn in 35.
Johnson's bogey-free start to the week ended when he almost went out of bounds at the par-four 10th on three separate occasions on his way to a double-bogey six, as McIlroy converted a five-foot birdie to close the gap to two.
After the pair exchanged birdies at the par-five 11th, Johnson increased his lead with a seven-foot gain at the next and moved four ahead when McIlroy failed to convert from four feet to save par at the 14th.
A stunning pitch from a tough lie from Johnson set up a tap-in birdie at the 15th, where McIlroy hit a brilliant approach under the trees but missed his 12-foot eagle attempt.
McIlroy made amends by converting from the same distance at the 16th but saw Johnson post a birdie-two from 15 feet at the 15th to restore his four-shot cushion.
Cameron Smith and Patrick Cantlay are the other two players sharing third, with Kiradech Aphibarnrat and Ian Poulter eight off the pace in tied-seventh.
A final-hole birdie saw Tiger Woods end the day under par and stay inside the top 10, despite carding a four-putt double-bogey and three-putt bogey in a two-hole stretch late in his round.
Watch the final round of the WGC-Mexico Championship live on Sunday from 5pm on Sky Sports Golf and Sky Sports Main Event.