Wyndham Clark led by two shots from fellow former U.S. Open champion Dustin Johnson at the completion of the weather-affected first round at Shinnecock Hills.
A two-hour fog delay early on day one meant 50 players returned at dawn amid clear skies to complete their opening round after play was suspended due to darkness at 8:25pm local time.
Among those, 2023 champion Clark, on a hot run of form that has seen him win on the PGA Tour last month, parred his two remaining holes – the eighth and ninth – to complete a first-round six-under-par 64.
Fellow American and playing partner Johnson, who won the first of his two Major Championships to date at this event a decade ago, birdied two of his three remaining holes to sit solo second.
After a double bogey late on Thursday, he began his Friday by rolling in a birdie putt at the par-three 16th before picking up another gain after hitting his approach to three feet at the last to finish at four under.
Five past U.S. Open champions are in the top six and ties after the opening round, with 2023 champion Matt Fitzpatrick and 2019 winner Gary Woodland among those at three under.
Among those to benefit from unexpected and relatively calm conditions during the afternoon wave on Thursday, Fitzpatrick birdied both the 16th and 17th before a par at the last saw him complete a 67.
Woodland is in the company of countryman Clark over the first two days and he picked up a shot at the eighth, his penultimate hole of the round, to also sit at three under.
A shot further back were Jon Rahm, who parred the five holes he had to finish, and American trio Sam Stevens, Spencer Tibbits and amateur Ryder Cowan.
Spaniard Angel Hidalgo, who came through qualifying to seal his spot, birdied the seventh after earlier resuming his first round to play his way into a group at one under that includes Ryder Cup duo Rory McIlroy and Ludvig Åberg.
The second round began at 06:50am local time, a 15-minute delay to the original intended tee times.
