Rickie Fowler sets the pace at US Open

Rickie Fowler produced a record-equalling low-scoring round to take a one-shot lead at the US Open as the big-hitters failed to fire.

Fowler, the world number nine from California, revelled in benign conditions at Erin Hills Golf Course to reel off seven birdies and 11 pars in a superb 65.

The 28-year-old's seven-under-par total matched the lowest to par score ever carded in the opening round of a US Open, a record shared by Jack Nicklaus and Tom Weiskopf since the 1980 tournament.

With the picturesque par-72 course set up at a monstrous 7,845 yards, Erin Hills had been expected to live up to the US Open's billing of being the toughest test in golf.

But heavy rain, which has softened greens and made fairways more forgiving, levelled the playing field dramatically.

Fowler wasted no time in exploiting the conditions after teeing off on the 10th, rattling off four quick birdies to be four under.

Three more birdies on his inward nine took him to seven under and a piece of US Open history.

"It's cool, but it's just the first round," Fowler said afterwards.

"It is always cool to be part of some sort of history in golf. But I'd rather be remembered for something that's done on Sunday."

Big-hitters flop

Fowler leads by one shot from England's Paul Casey and lowly-ranked American Xander Schauffele.

Casey carded an eagle and six birdies for a six-under-par 66 while Schauffele, the 23-year-old world number 352 also carded a 66.

Yet while Fowler and Casey thrived, defending champion Dustin Johnson, world number two Rory McIlroy and world number three Jason Day -- three big-hitters who had been tipped to thrive -- all had a day to forget.

Johnson blamed an errant putter for his three-over-par 75, which included a double-bogey and two bogeys.

"I just didn't putt very well," Johnson said. "I missed a lot of really good opportunities. That was the big key for me."

McIlroy, who is returning to action after a rib injury, opened with an early eagle but was unable to maintain his momentum and finished with a six-over-par 78.

"Just timing was a little bit off, and that was it," McIlroy said.

"Just really bad tee shots which led to obviously not being able to give myself many looks for birdies."

Day meanwhile was left sliding towards an early exit after a calamitous seven-over-par 79.

With Johnson, McIlroy and Day misfiring, it was left to a clutch of unheralded players to dominate the upper reaches of the leaderboard.

Three players -- Brian Harman, Tommy Fleetwood and Brooks Koepka -- were in the clubhouse on five under, two back from Fowler.

Sergio lurking

Masters champion Sergio Garcia meanwhile was lurking five off the lead after a two-under-par 70.

Garcia carded an eagle, three birdies and three bogeys in a roller coaster round.

Former US Open champion Ernie Els chose the 20th anniversary of his last victory in the tournament to remind fans that he is not quite ready to be put out to grass.

The 47-year-old South African posted a two-under-par 71. His round would have been better had it not been for two bogeys in his closing holes.

"All in all, I've got to be happy," Els said. "You take a two-under-par in the first round in the US Open, you're right there."

Thursday's opening round began with drama off the course after a blimp hovering near the venue crashed.

Players and fans looked on in disbelief as the aircraft fell from the sky near the venue.

The pilot was later being treated for burns, local law enforcement officials said.

The incident stunned golfers and fans who witnessed it.

"I was teeing off and I looked up and saw it on fire, and I felt sick to my stomach," American Jamie Lovemark said. "I felt terrible for the people inside. I didn't know what was going on. It was a horrible sight."

The US Golf Association later confirmed the blimp was not affiliated to the tournament.

"Our thoughts and prayers are with the pilot at this time," the USGA said in a statement.