Bryson DeChambeau and Brooks Koepka
CNN  — 

Heading into this week’s U.S. Open, the on and off course shenanigans between Brooks Koepka and Bryson DeChambeau had dominated the headlines.

Ever since Koepka’s eye-roll reaction to DeChambeau walking behind him at last month’s PGA Championship, the pair have exchanged barbs, although they have both since said they believe their rivalry is good for golf.

And just when we thought the golf at the third major of the season might take center stage at Thursday’s opening round at Torrey Pines, DeChambeua upped the ante.

DeChambeau plays his shot from the fifth tee during the first round of the 2021 U.S. Open.

After Koepka’s opening round two-under 69, Koepka was preparing for his post-round interview with Todd Lewis for the Golf Channel.

However, unbeknown to him, DeChambeau happened to be walking behind him just out of shot, this time walking on grass so he was not making any noise.

But, DeChambeau – dressed in his customary white hat – then took the moment to jump and wave his left arm, all of which was captured on camera.

While the incident at May’s PGA Championship that sparked all this drama was an accident, according to reigning U.S. Open winner DeChambeau, this time, he decided to have some “fun with it.”

“It’s one of those things people are thinking I was doing something, I wasn’t doing anything at the PGA Championship,” DeChambeau told the media after his round on Thursday.

“I saw an opportunity and I just had fun with it.”

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Koepka hits from the fourth tee during the first round of the U.S. Open.

Battling the conditions

The U.S. Open’s first round was delayed by around 90 minutes because of morning fog at the California course.

The delay meant that 36 players did not finish their opening rounds, and will have to complete them on Friday morning.

Of those who were able to handle the elements, Russell Henley and Louis Oosthuizen prospered, finishing Thursday tied at the top of the leaderboard on four-under par.

American Henley, who is ranked world No. 63, shot a 67, while Oosthuizen was one of the players who wasn’t able to finish his round because of loss of light, as the horn which signaled the end of play went off while he was playing the 17th hole.

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Henley plays on the practice range during a fog-delayed first round of the 2021 U.S. Open.

“I’ve gotten hot a few times and won some TOUR events for sure, but consistently I think the last year or so has been my best year, and I feel good about it,” Henley told reporters.

“I feel like I have more of a complete game. But I haven’t finished top 10 in majors or anything. Haven’t really been in the majors. I want to make that better, play better in the majors.”

Francesco Molinari and Rafael Cabrera sit one shot behind the leaders, while Hayden Buckley, Hideki Matsuyama, Jon Rahm, Koepka, Xander Schauffele and Sebastian Munoz sit two shots of the leaders at two-under.

Four-time major winner Rory McIlroy had to rush to finish his last few holes, literally jogging up the 18th before rolling in a birdie to finish one under.