Washington - Justin Thomas humbled rain-softened Medinah with dazzling shotmaking on Saturday, firing a course-record 11-under par 61 to seize a six-stroke lead after the third round of the BMW Championship.
An incredible day for the 2017 PGA Championship winner left the 26-year-old American on 21-under 195 after 54 holes at the suburban Chicago layout.
"It was just one of those freaky days when you get in a zone," Thomas said.
"It was just one of those days when you hit it unbelievable.
"I was able to put it close to the holes and make the putts. One of those days."
The day-old course record of 63 set by Japan's Hideki Matsuyama was shattered by Thomas, whose first-round 65 on Thursday had shared the course record.
"I just hope the trend doesn't continue and someone else breaks it tomorrow," Thomas said.
Americans Tony Finau and Patrick Cantlay were a distant second on 201 after each shot 68 with Slovakia's Rory Sabbatini another stroke adrift and Spain's Jon Rahm fifth on 205.
Thomas birdied the first five holes, answered a bogey at six with a birdie at the par-5 eighth, hit an amazing approach at the par-5 10th to set up a tap-in eagle and sank a 22-foot birdie chip from the rough at the par-5 14th.
And he wasn't done. Not even close.
Thomas found water off the tee at the par-4 15th, then dropped a 63-yard shot two feet from the cup to rescue a tap-in par.
At the par-4 16th, Thomas holed out for eagle with an 8-iron from 181 yards, his uphill blast perfect without a view of the flagstick.
"It looked good in the air," Thomas said.
"It was nice. That's something that was just a little bit of a bonus."
At the par-3 17th, Thomas landed the ball six feet from the cup and sank the birdie putt.
"I hit a lot of great shots today but that (tee shot) was an under-rated one," Thomas said.
"I was so pumped up. Took a little off it and feathered it perfectly."
Thomas rolled the ball past the cup on a 29-foot birdie putt at the par-4 18th then sank his four-footer for par to close a spectacular performance.
"I'm trying to win by as many as I possibly can," Thomas said.
"This course is going to be gettable tomorrow and a lot of guys could do what I did today. I'm going to have a have another good round and see if we can make some history."
The playoff event will decide the 30 season points leaders who qualify for next week's showdown at East Lake in Atlanta.
Reigning Masters champion Tiger Woods matched his lowest round since February with a 67 while reigning US Open champion Gary Woodland shot 64.
Sixth-ranked Woods, trying to finish well enough to qualify for a chance at defending his title in next week's season-ending Tour Championship, was on 209, sharing 31st at the course where he won the 1999 and 2006 PGA Championships.
"This was nice to at least give myself a chance to make it to next week," said Woods, who likely needs a top-12 finish to book a spot in Atlanta next week.
Woods had not shot a lower 18 holes since firing a 66 in the second round of the WGC Mexico Championship. He had not fired a bogey-free round since last year's BMW third round at Aronimink.
Woodland's 64 had been the second-best round ever at Medinah, but only for a few hours thanks to Thomas.
Brandt Snedeker made two amazing chip shots for birdies on par-3 holes, holing out a 35-yarder from deep rough at 13 and blasting out of a greenside bunker from 60 feet and rolling the ball into the cup at 17. He fired a 67 to share sixth on 204 with Lucas Glover and Canada's Corey Conners.
Leading scores after Saturday's third round of the BMW Championship at Medinah in suburban Chicago: (par 72, USA unless noted):
195 - Justin Thomas 65-69-61
201 - Tony Finau 67-66-68, Patrick Cantlay 66-67-68
202 - Rory Sabbatini (SVK) 67-68-67
203 - Jon Rahm (ESP) 68-69-66
204 - Brandt Snedeker 66-71-67, Corey Conners (CAN) 69-66-69, Lucas Glover 66-69-69
205 - Rickie Fowler 67-70-68, Kevin Kisner 68-68-69, Xander Schauffele 67-68-70, Hideki Matsuyama (JPN) 69-63-73
206 - Joel Dahmen 66-71-69, Rory McIlroy (NIR) 69-67-70, Kevin Tway 69-67-70, Tommy Fleetwood 70-66-70, Adam Hadwin (CAN) 67-68-71
207 - Gary Woodland 70-73-64, Wyndham Clark 69-73-65, Paul Casey (ENG) 70-70-67, Patrick Reed 68-71-68, Louis Oosthuizen (RSA) 70-69-68, Adam Scott (AUS) 67-71-69
208 - J.T. Poston 68-74-66, Im Sung-jae (KOR) 70-72-66, Joaquin Niemann (CHI) 74-65-69, C.T. Pan (TPE) 71-67-70, Jason Kokrak 65-73-70, Max Homa 70-67-71, Kim Si-woo (KOR) 70-67-71