Brooks Koepka's brutal US Open omen for rival Bryson DeChambeau

The increasingly hostile rivalry between American golfers Brooks Koepka and Bryson DeChambeau was arguably the most discussed topic in the lead-up to opening round at the US Open.

When the dust settled on both of their opening rounds at Torrey Pines on Friday, it was Koepka that enjoyed the last laugh.

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Koepka made an impressive start to his bid for a third US Open victory in five years but Phil Mickelson's hopes of completing the career grand slam suffered a significant blow.

Four-time major winner Koepka, who claimed the US Open in 2017 and 2018 and was second in 2019, carded an opening 69 to lie two shots behind early clubhouse leaders Russell Henley and Louis Oosthuizen - the latter of whom only completed 16 holes before bad light ended play.

Koepka's open dislike of DeChambeau was thrust back into the spotlight after a clip that went viral of him reacting in disgust during an interview after spotting his noisy rival in the background.

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.

DeChambeau did have his moments though, with a brilliantly judged long birdie putt at the par-thee 8th hole a standout for the 27-year-old.

The reigning champion also managed to grab another birdie at 18 to finish at two-over after the first round - six shots off clubhouse leaders Henley and Oosthuizen.

The 31-year-old Koepka — who won consecutive US Open titles in 2017 and 2018 — fired four birdies and two bogeys on the day and sits two shots behind co-leaders Henley and Oosthuizen on four-under, and one shot behind European duo Francesco Molinari and Rafa Cabrera Bello.

Former Open champion 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.

Mickelson struggles in grand slam quest

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.

The exemption was required because Mickelson had slipped out of the world's top 100 and the prospect of him joining Gene Sarazen, Ben Hogan, Gary Player, Jack Nicklaus and Tiger Woods in having won all four majors looked increasingly far-fetched.

However, Mickelson's stunning victory at Kiawah Island came with a five-year US Open exemption and the 51-year-old, who celebrated his birthday on Wednesday, spent last week practising hard at a course he used to love.

Adam Scott is the best placed Australian in a tie for 10th after back-to-back birdies on 17 and 18 left him three strokes off the lead after an opening round 70.

with AAP

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