Patrick Cantlay racked up six birdies on his way to a 5-under-par 65 and the lead among early finishers on Thursday in the US Open at Pinehurst, North Carolina.
Sweden's Ludvig Aberg shot 66 to hold second place after about four dozen golfers had completed their rounds.
France's Matthieu Pavon had a pair of eagles during the first 10 holes on the way to a 67.
Tony Finau shot 68, while the trio of South Korea's SH Kim, Canada's Corey Conners and Spain's Sergio Garcia all completed rounds of 69.
Golfers had to negotiate the tricky greens on Pinehurst No. 2 along with the increasing heat of the day.
It was a rough day for Tiger Woods, who shot 74 with two birdies -- both on the par-5 holes -- and six bogeys.
Some golfers aren't scheduled to begin their rounds until close to 2:45 pm local time. World No. 1 golfer Scott Scheffler had a tee time in the early afternoon after many golfers were done for the day.
Cantlay began the round on No. 10. He got better later in the round, with four birdies on the first eight holes on the front side.
Pavon became the first golfer to ever record multiple eagles in the same US Open round at Pinehurst. His first breakthrough came with an eagle on No. 5 and the second at No. 10 -- the course's two par-5 holes.
He rolled in long putts each time and reached 5 under before his first bogey on the par-4 11th.
After the second eagle, Pavon played the final eight holes at 2 over.
Woods, who began the round on the back nine, birdied his first hole. But a seven-hole stretch with five bogeys sent him tumbling down the standings.
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