Brooks Koepka saw his position at the top of the US PGA Championship leaderboard significantly strengthened long before he was due to tee off on day two.
Reigning champion Koepka carded a sensational 63 in round one to set a new course at Bethpage Black, but ended Thursday leading by just a single shot after Danny Lee managed a superb six-under score.
However, Lee bogeyed his second and third holes after starting at the 10th on Friday morning and then ran up a double-bogey six at the long 15th to slip back into a tie for third.
That meant Koepka, who was scheduled to begin his second round at 1:49pm local time (6:49pm BST), found himself four clear of nearest rival Tommy Fleetwood, another of the afternoon starters on Friday.
Most of the first-round frontrunners were set to head out in the latter half of the day, but Jordan Spieth, Dustin Johnson, Phil Mickelson and Jason Day were all part of the morning wave and seeking to improve on scores of one under.
Tiger Woods and Francesco Molinari - Koepka's playing partners - were back at two over, the same score as 2012 and 2014 PGA winner Rory McIlroy.