Shane Lowry showed once again that he has the game to contend for major when he chiseled out a career low US Open round with an opening 69 at Chambers Bay.

As Darren Clarke struggled to a 77, Tiger Woods slumped to an 80 and Rickie Fowler crashed to an 82 in tricky afternoon conditions, the pride of Co Offaly ended the day just outside the the top 10 after knocking three shots off his previous best score in a US Open.

Starting on the back nine in tougher afternoon conditions when the greens were bumpier and the wind got up, Lowry bogeyed the 13th but then caught fire before the turn with birdies at the par-three 15th and 17th and a birdie four at the 18th.

Comfortably inside the top 10 on two under, he slipped back with a bogeys at the third and seventh but birdied the par-five eighth and then came up just short with a slick birdie putt from around 20 feet at the par-three ninth.

He ended the day tied for 14th with the likes of Phil Mickelson on one under with a chance to score well ahead of him.

He was certainly helped by playing with American Ben Martin, who grabbed a share of the leaden five under with seven holes to go but dropped two shots coming in.

While Jordan Spieth and Jason Day showed why they're fancied for the title as they posted 68s in the afternoon, others had their struggles. 

Justin Rose was one under with four to play and bogeyed the three of the last four to drop to tied 53rd with the likes of Rory McIlroy after a 72.

It was far worse for Fowler and Woods who will need sensational second rounds to make the cut for the Top 60 and ties.

Fowler dropped eight shots in four holes from the sixth and despite a tap in eagle two at the 10th, he eventually shot an 11 over 81.

That was one shot worse that Woods, who hardly hit a fairway as he followed seven birdies with a triple at the 14th.

He looked en route to break 80 when he birdied the 16th but he topped his approach tot he 18th into a bunker and took six.

Woods promised to keep going despite his latest set back.

"I fought, I fought hard. And that was my number. I couldn't grind out any harder than that. So that's just the way I played and unfortunately it was a high number today," Woods said. 

Rose was disappointed with his finish, admitting: "I threw my round away at the end. I could or should have been three-under par, probably through about 12 or 13. But I just couldn't get the ball in the hole and just a really weak finish, some poor clubs and some tired, lazy swings at the end.

"All in all, a little bit disappointed. I felt like I finished poorly, but I felt like I could have gotten a lot more out of the day."

Like many, he found the greens hard to take.

"I really hope the greens roll better in the morning because it wasn't a lot of fun out there in the afternoon. I couldn't see a putt staying on the line I hit it on and makes it a little frustrating at times. I'm hoping I can get some good looks at it tomorrow and the ball rolls a little truer, so I feel like I can make some birdies."

Masters champion Spieth didn't play his best but he holed his share of putts and posted a good score.

"I didn't strike the ball particularly well. I wasn't pleased with the way I hit it," he said. "I thought I putted well. I missed a couple putts inside ten feet, but that's going to happen out here. That's inconsistency on the greens. I made a lot of them from inside ten feet, too."

Spieth enjoyed his round with Rose and Day and the Australian was certainly pleased to shoot 68 after making two bogeys and a double bogey at the par-three 15th, where he came up short.

"Yes, it was tough this afternoon, it was very, very tough. Bloody 15th hole, down the hill. But looks, everyone was coming up short there, because we - our group kind of made a mess of it. It was a tough one. Glad to come back with a birdie on the 16th.

"That's a U.S. Open golf course, you shoot anything under par on the first round — even though the conditions were a little easier this morning, a lot more gettable this morning, but I played solid golf coming in."

Clarke double bogeyed the first and bogeyed the second en route to a 77 that will be remembered for the tiddler he missed on the first.