Cantlay established the lead early in the day, and McIlroy – the 2011 champion – had birdies on two of the final three holes playing in the afternoon.

Sweden's Ludvig Aberg shot 66 to hold third place.

France's Matthieu Pavon had a pair of eagles during the first 10 holes. He ended up shooting 67, a mark later matched by 2020 champion Bryson DeChambeau.

Tony Finau, Akshay Bhatia from nearby Raleigh and England's Tyrrell Hatton shot 68s to share sixth place.

Golfers had to negotiate the tricky greens on Pinehurst No.2 along with the increasing heat of 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.

Patrick Cantlay leads a major for the first time in his career. PHOTO: Getty Images.

"Feeling good about my game," he said. "I've been working hard. I have to just keep putting myself in the fairway, giving myself opportunities and I did a good job of that."

This is the first time Cantlay has led or co-led in a major.

Pavon became the first golfer to ever record multiple eagles in the same U.S Open round at Pinehurst. His first breakthrough came with an eagle on No.5 and later on No.10 – the course's two par-5 holes – where he rolled in putts of 18 feet and 27 feet.

He reached five-under before his first bogey on the par-4 11th.

After the second eagle, Pavon played the final eight holes in two-over.

World No.1 Scottie Scheffler had a lacklustre 71. Defending champion Wyndham Clark managed just one birdie during his round of 73.