American pair Phil Mickelson and Justin Thomas took over at the top of the leaderboard midway through the final round of the WGC – Mexico Championship at Chapultepec Golf Club.
With overnight leader Shubhankar Sharma turning in one over par to drop to 12 under, Mickelson and Thomas advanced to 14 under but there were a host of players still in with a chance heading into the closing holes.
US PGA Championship winner Thomas was 11 shots behind halfway leader Sharma on Friday night but, after a blistering 62 on Saturday, carded five birdies in his first 12 holes on Sunday as his remarkable weekend continued.
Mickelson began the day with birdies at the first and second – he almost chipped in for eagle on the latter – only to three-putt the third.
However, he responded with gains from 15 feet on the fourth and tap-in range on the sixth and found himself at the head of the pack after turning in 32.
Spain's Rafa Cabrera Bello had chipped in from the sand for eagle at the first to wipe out Sharma's lead before the Race to Dubai leader had even teed off, and remained one back on 13 under after recovering from a bogey on the fifth with a close-range birdie at the seventh to sit alongside Tyrrell Hatton.
England's Hatton had also enjoyed a spell at the top of the leaderboard after three birdies in his first four holes, only to then bogey the sixth following a wayward drive.
Sharma, Thailand's Kiradech Aphibarnrat and American Brian Harman were all at 12 under, with World Number One Dustin Johnson still not out of it a shot further back, although with only seven holes remaining the defending champion was in need of quick gains.
Mickelson hit his approach to four feet at the tenth and birdied to grab the outright lead.
The chasing pack swelled as Aphibarnrat chipped in from a bunker at the 13th to reach 13 under and Harman joined him by converting a 25 footer on the 12th – although he spurned a chance from three feet at the next to move alongside Thomas.