Rory McIlroy carded a breathless 64 to reach seven-under par and the clubhouse lead in the Masters, where Scottie Scheffler is on course to deny him a career grand slam.
McIlroy holed out for birdie at the 18th hole having found a greenside bunker with his approach, sparking jubilant scenes as he completed the best round of the week by fully three shots.
It was enough to go clear of the rest of the chasing pack in second place, but leader Scottie Scheffler's scrambled pars at the 11th and 12th holes ensured he would take a three-shot lead over McIlroy to the closing stretch.
Scheffler then hit a brilliant wedge to the 14th hole to set up birdie and restore a four-shot cushion with four holes to play, a Green Jacket now within touching distance.
Cameron Smith had closed the gap to two with birdie at the 11th hole only to find water at the famous 12th, running up a triple-bogey which ended his hopes of becoming the second Australian to win the Masters.
As Smith played the 14th, he'd been joined in third by Collin Morikawa, who matched playing partner McIlroy's hole-out bunker at the 18th to post his first Masters top-10.
Joyful McIlroy toasts best ever Masters round
"Yeah, by far," said McIlroy, asked if it was his best experience at Augusta. "I got off to a great start today and I just kept it rolling. I knew I needed my best ever score to at least have a chance. It's probably not going to be low enough, but I can't ask any more of myself. I played a really, really good round of golf and maybe I'll come up just a little short but it's the most fun I've had on a golf course for a very long time.
"I really just wanted to post a number, and I kept thinking to myself 'why not me?'. I feel like I'm playing well, we finally had conditions where you can get after it a bit and shoot a low one. When I birdied one, I thought 'this could be it today'. I stayed aggressive, kept hitting good shots and hitting good putts.
"I'm getting the hang of this place after 14 years of trying! Whatever happens over the next couple of hours, I'll keep coming back, and keep trying."