Fowler, who held a one shot advantage overnight, cruised through an error free front nine that included two birdies. Jack Nicklaus and Tom Weiskopf each shot 7-under 63 in the first round at Baltusrol in the 1980 U.S. Open.

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

"It is always cool to be part of some sort of history in golf".

"My short game was great at Wentworth (in the BMW PGA Championship) but my ball-striking is really coming back to its best now and if I keep going then there's no reason I can't be in contention on Sunday".

Fowler enters Friday's second round with a one-shot lead over Paul Casey and Tommy Schauffele.

Casey started the second round just one shot behind Rickie Fowler, and he tied Fowler briefly with a birdie on the par-4 11th hole before dropping a shot on the 12th.

World No. 1 Dustin Johnson opened defence of his crown with a shaky three-over 75, while No. 2 Rory McIlroy, sidelined for much of the year with rib and back injuries, opened with an eagle but could not shake the rust, fading to six-over 78 after being punished by the brutal fescue rough several times. After teeing off on the 10th hole in one of the day's final groups, he bogeyed two of his first four holes.

"There's nothing I can hide behind; I just have to go out there and get it done".

"There are a lot of things I could have done better today, obviously", McIlroy said. "That was the big key for me".

"It really isn't about the score", he said. The Englishman has roared back to life with four straight birdies and is back to being one shot off the lead.

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

However, of the leading 18 not one has tasted success in a Major and, in fact, you have to look down to those sharing 19 place before singling out a Major Champion and they are reigning Masters victor Sergio Garcia (71) and double Major winning Martin Kaymer (69) at three under. "It was a bit of a roller coaster".

Westwood's 69 was just the third time the former world number one has broken 70 in the first round of the US Open, with his lowest score of 67 coming past year. It's been a tough year for the 47-year-old whose body hasn't been feeling as smooth as his trademark swing recently.

"Even though it's very disappointing to not be here on the weekend, I think these last two rounds will serve me well going into the summer", McIlroy said.

Thursday's opening round began with drama off the course after a blimp hovering near the venue crashed. He hammered it as hard as he could and looked up toward the sky to see where it went.

But if he does, there's no doubt who the fan favorite will be for the next few days. Jamie Lovemark said he was teeing off when he looked up and saw the blimp on fire. I felt awful for the people inside. USGA officials informed the public late Thursday that water line to the station was immediately cut off when test results came back positive. It was a frightful sight.

"We had a big conversation at the end of the year and he didn't like it", Harmon said recently on Sky Sports, where he works as an analyst during golf tournaments.

"I was just trying to have half as good a round as Rickie had", said Casey, who played in the afternoon.