American Justin Thomas carded a spectacular 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 Thomas, who broke by two strokes the previous best score at Medinah, set just 24 hours previously by Hideki Matsuyama.
Halfway leader Matsuyama could not replicate that performance on Saturday, plunging 10 strokes behind with a 73.
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.
Thomas started his round with five successive birdies, and later recorded a tap-in eagle at the par-five 10th.
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.
Thomas finished with two eagles, eight birdies and one bogey.