Gary Woodland set a new lowest 36-hole score at the US PGA Championship by shooting a four-under 66 to continue leading at Bellerive on day two.
Following his opening-round 64, the American became the fifth man to card 130 at the halfway stage of a major.
At 10 under he is one clear of Kevin Kisner, who had a six-under 64.
US Open champion Brooks Koepka and Charl Schwartzel both missed putts on the last for 62s that would have equalled the lowest round in a major.
American Koepka moved to eight under for the tournament with seven birdies in his bogey-free 63, missing a 20-foot putt on the ninth to match Branden Grace’s 62 set at the 2017 Open.
South African Schwartzel, who holed eight birdies, is a shot behind after climbing 44 places up the leaderboard on Friday.
It is only the second time that two players have shot 63 on the same day at a major, after Jack Nicklaus and Tom Weiskopf at the 1980 US Open.
World number one Dustin Johnson and Belgium’s Thomas Pieters are level with Schwartzel after carding 66s.
Defending champion Justin Thomas, two-time winner Rory McIlroy and 14-time major champion Tiger Woods are among the later starters.
Woodland and Kisner jostle for clubhouse lead
Woodland, who has never finished inside the top 10 at a major in 27 previous attempts, led after the first round on six under and extended his advantage with a birdie on the 11th after starting on the back nine.
However, the 34-year-old American saw playing partner Kisner surge ahead in a blistering start.
Open Championship runner-up Kisner holed six birdies as he played his first nine holes in 29 shots to move into the lead on nine under, while Woodland avenged a bogey on the 14th with an eagle three on the par-five 17th.
That left Woodland a shot behind Kisner going into the front nine – where the pair continued to exchange the lead in a thrilling battle.
Successive birdies for Woodland on the second and third moved him back into the lead at 10 under, a bogey on the fourth dropping him back alongside Kisner who strung together six consecutive pars.
Kisner birdied the seventh to move clear at 10 under but Woodland picked up a shot on the next to join him before Kisner bogeyed the ninth.
That meant the 34-year-old American missed out on recording a record-equalling round of 63 like Koepka and Schwartzel.
More to follow.