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Brooks Koepka has made no secret of his disdain for big-hitting rival Bryson DeChambeau.
The lead-up to the US Open has been dominated by talk of the frosty relationship between the pair, despite them being unlikely to see each other on course.
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Koepka's lack of respect for DeChambeau was on full display in a memorable viral video from a few weeks ago, in which the mere sight of DeChambeau was enough to throw Koepka in the middle of a media appearance.
That video evidently hasn't stopped DeChambeau from attempting to mess with Koepka, with the former videobombing the two-time US Open winner after the first round at Torrey Pines.
Koepka finished two strokes behind leaders Louis Oosthuizen and Russell Henley, while DeChambeau turned in a two-over par effort to finish six shots behind.
DeChambeau waved a hand in the back of the shot as Koepka discussed his promising opening round as he pursues a third US Open title.
Following his opening round at Torrey Pines, Koepka referenced an age-old adage in golf that ended up proving to be a bad omen for his fierce rival.
“You can’t win it today, but you can definitely lose it,” Koepka said after his opening round 69 that left him two shots off the lead.
“Pretty pleased. Not the best, but I’ll definitely take it.”
While Koepka was pleased with his first 18 holes, the same couldn't be said about DeChambeau who seriously damaged his chances of defending the title with a shocking collapse.
DeChambeau found trouble at the turn as he suffered three bogeys in a row through holes 11 to 13, before finally stemming the bleeding with a birdie at 14.
A chaotic day for DeChambeau also included three bogeys on the front nine to leave him facing a mountain to climb if he's to successfully defend his 2020 title.
Koepka starts well but Phil Mickelson struggling at US Open
Former Open champion Francesco Molinari was a shot off the lead following a 68, but Mickelson finished four over, a month after becoming the oldest champion in major history with his shock victory in the US PGA Championship.
Starting on the back nine, Koepka birdied the 12th, 17th and 18th to reach the turn in 33 before another birdie on the second took him into the outright lead on four under.
A wild tee shot to the third cost the 31-year-old his first bogey of the day and another shot went on the seventh after a pulled drive which finished at the base of a picnic bench where spectators were eating lunch.
Also starting on the back nine after a 90-minute delay due to fog, Mickelson dropped a shot on the 10th when he failed to get up and down from a greenside bunker, his par attempt catching the edge of the hole and spinning out.
The six-time major winner was even more unfortunate on the 13th when, after taking a penalty drop from a bush, his fourth shot to the 613-yard par five bounced once before hitting the pin and rebounding off the green.
Mickelson did well to limit the damage to a single shot by chipping to six feet and holing the putt, but another shot went on the 15th after an errant drive.
A birdie on the 17th stopped the rot and Mickelson also found the green on the par-five 18th in two, but could only three-putt from 60 feet for par.
Just nine days before rolling back the years to win the US PGA, Mickelson had reluctantly accepted a special exemption for the US Open, an event in which he has finished runner-up a record six times.
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