Kiwi golfer Danny Lee was among the early PGA Championship leaders at New York's Bethpage Black course on Friday (NZT).
After the opening round of six-under-par 64, Lee sits outright second, just one shot behind defending champion Brooks Keopka of the United States.
In a remarkably steady performance, Lee gathered eight birdies through 18 holes - including back to back on the eighth and ninth, and again on the 17th and 18th - but also two bogies, as most of the field struggled to beat par.
Lee's best performance at a Major is a tie for 17th at the 2016 US Masters. This was his lowest score in a Major tournament.
Koepka quickly stamped his dominance on the event, firing a course-record to tie the championship-low round and take the clubhouse lead during an eventful first round.
Koepka's 63 was the 17th time the score has been recorded in PGA Championship history, but he became the first player to do it twice.
The 29-year-old from Florida carded a 63 in round two when he won last year.
Three-time Major champion Koepka is just the third golfer with multiple rounds of 63 at Majors, joining Australia's Greg Norman and Fiji's Vijay Singh.
At the notoriously difficult 7459-yard Bethpage, Koepka made no mistakes, as he amassed seven birdies and zero bogeys to equal his lowest round in relation to par at the Majors.
With play still underway, Koepka held a three-shot lead over, with England's Tommy Fleetwood (67) at three under.
Koepka said it was satisfying to make a statement on day one, with so much hype surrounding playing partner Tiger Woods, who won his 15th Major at the Masters in April.
"It was great that Tiger won Augusta, but we're at a new week now," Koepka said.
"Obviously, everybody in New York is going to be cheering for him and it's going to be loud, especially if he makes a putt.
"You've just got to keep battling and find a way to get through it."
Woods, who struggled to a 72, claimed Koepka could have shot a lower score, given he did not birdie either of the two par-fives.
"I think that was probably the [worst] score he could have shot today," Woods said. "He left a few out there with a couple putts that he missed, but it could have easily been a couple better."
Woods poured cold water on hopes of winning back-to-back Majors, with his month-long rest after winning the Masters in April clearly leaving some rust.
His rollercoaster 72 included two double-bogeys, three bogeys, a long-range eagle and three birdies, which left him at two over.
Kiwi Ryan Fox blew out to eight-over for the day, including seven bogies, a double bogie and just one birdy, and will now struggle to make the cut on Saturday.