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"I couldn't grind out any harder than that. So that's just the way I played and unfortunately it was a high number."

US Open Venue: Chambers Bay, Washington Dates: 18-21 June Coverage: Live commentary on the final two rounds on BBC Radio 5 live Saturday and Sunday 22:00-03:00. Live text updates from 19:00 BST of every round on the BBC Sport website. Read full details here

Three-time winner Tiger Woods says he is lacking consistency and is still rusty following back surgery after making a "tough" start to the US Open.

Woods, 39, shot a 10-over-par 80 in the first round at Chambers Bay, and is already 15 shots behind external-link the leaders.

"It's one of those things, I've just got to work through it," the former world number one said.

"I'm trying as hard as I can to do it, I just can't get the consistency that I'd like to have out there."

Analysis: Iain Carter, BBC Sport golf correspondent "Woods looked utterly lost from the moment he struck a horrible second shot into the rough at the first.He dropped four shots in his first six holes, his club flew from his hands as he hacked from the rough on the eighth and he racked up a triple bogey at the 14th.At the last he embarrassingly topped his second shot on route to the 80 - his second worst round in a major.It's being suggested he should take yet another break from the game and Woods ability to compete again at the highest level is increasingly open to question."

Fourteen-time major winner Woods registered a triple bogey on the 14th and is well behind leaders Dustin Johnson of America and Sweden's Henrik Stenson who are on five under.

Only Rich Berberian Jr, a club professional playing in his first US Open, and Rickie Fowler had worse rounds.

A birdie at the 16th was the lone bright spot before Woods finished with a bogey to leave him tied 152nd, one shot clear of Fowler and three in front of Berberian.

Woods has been hampered by a back problem for some time.

The American missed the 2014 Masters, a competition he has won four times, after having surgery on a pinched nerve in his back before withdrawing from the 2014 US Open.

Woods also withdrew from the Farmers Insurance Open at Torrey Pines in February because of it.

It was the par-four holes that proved most problematic for Woods with eight bogeys and a triple-bogey seven

"I haven't played enough. I haven't had a rhythm to my play," added the 2000, 2002 and 2008 US Open winner.

"I didn't play much last year and I haven't played much this year. Knee surgeries are pretty easy compared to a back surgery and, for some reason, it's just a lot harder dealing with a nerve than a joint."

Asked if he was on the right track, Woods added: "Yeah, I am, I am. I know when I do it right, it's so easy.

"I just need to do it more often and build from there.

Woods by numbers 15 - shots off the lead. 195 - current world ranking. 9 - bogeys or worse, including a triple-bogey seven on the 14th. 27 - majors played since Woods won the last of his 14 in 2008. 152 - round leaves him in a tie for 152nd place, with only two players having fared worse on day one. 81 - Woods' worst round at a major, at the Open Championship in 2002. 105 - width of the 13th fairway at Chambers Bay in yards, the widest in US Open history; Woods missed it. 302 - worst four-round total of his career, which also included a career-worst 85, recorded on his last outing at the Memorial Tournament earlier this month.

"I've gone through tough phases before and I've come out OK on the other side."

Woods, without a major title since his US Open victory seven years ago at Torrey Pines, added: "I fought, I fought hard.

"I couldn't grind out any harder than that. So that's just the way I played and unfortunately it was a high number."

Despite his round, Woods was still able to find a bit of humour in his performance.

"The bright side is at least I kicked Rickie's [Fowler] butt," he joked.

One hack out of the rough led Woods to lose grip on his club and he watched as it disappeared over his shoulder