(Reuters) - Justin Thomas enjoyed "one of those freaky days in the zone" as he carded a course-record 11-under-par 61 to vault to a six-stroke lead in the third round at the BMW Championship in suburban Chicago on Saturday.
An eagle with an eight-iron from 180 yards at the par-four 16th was just one highlight of an eventful day for the American, who broke by two strokes the previous best score at Medinah, set just 24 hours previously by Hideki Matsuyama.
Thomas posted a 21-under 195 total in the penultimate event of the PGA Tour season, while compatriots Tony Finau and Patrick Cantlay fired 68s for a share of second place on 15-under.
Halfway leader Matsuyama plunged 10 strokes behind with a 73.
"I hit the ball pretty unbelievable," Thomas told broadcaster NBC after his fourth career round of 61 or better.
"It's not like I made any long putts. I hit it close to the hole, and took advantage of some opportunities.
"I got a couple of good breaks and that's stuff that happens when you shoot 11 under."
Thomas started his round with five successive birdies, and later recorded a tap-in eagle at the par-five 10th after a precise five-wood approach shot.
The highlight reel continued when he chipped in from 20 feet from lush rough to birdie the 14th hole.
He then drove his tee shot into a pond at the 15th and took a penalty stroke, but still saved par, setting the stage for his most unlikely eagle at the par-four 16th, where his ball landed a couple of yards in front of the cup and trickled in.
"It looked good in the air," said the 26-year-old. "That's a little bit of a bonus."
Thomas finished with two eagles, eight birdies and one bogey, and vowed to continue attacking the rain-softened course in the final round.
"I'm trying to win by as many as I possibly can. If I just keep playing how I've been playing I feel like I can shoot another good round."
The performance was a reminder of the talent possessed by Thomas, who clinched his first major title two years ago at the PGA Championship and has been ranked number one in the world.
But his 2019 campaign suffered a setback when he injured a wrist in March and he eventually took six weeks off to let it heal, missing the PGA Championship before failing to make the cut at the U.S. Open.
If Thomas wins, he will start next week's season-ending Tour Championship in Atlanta as the top seed, with a two-stroke headstart over the second seed in the 30-man field, which may not include last year's winner Tiger Woods.
Woods shot 67 on Saturday to improve to equal 31st, but is projected to need a top-six finish to advance to East Lake, where he ended a five-year victory drought last year after returning from major back surgery.
"This was nice to at least give myself a chance to make it to next week," the 15-times major champion said of his round.
"It has been in the back of my mind to get there (to East Lake)."