Venue: Royal Troon Dates: Thu 18-Sun 21 July
Coverage: Live radio and text commentary on BBC Sport website, with video clips each day. Daily highlights programme on BBC Two from 20:00 BST. Click for full details.
A frustrated and disconsolate Rory McIlroy signed for a seven-over 78 as his quest to win a second Open title floundered on a wet and windy opening day at Royal Troon.
The world number two finished 10 shots behind American two-time major winner Justin Thomas, who rolled in a 25-footer at the last, to set the clubhouse target on three under.
A downbeat McIlroy said it "was one of those days where I just didn't adapt well enough to the conditions" before adding that his approach on Friday would simply be "to focus on trying to make the cut".
England's Justin Rose, who came through qualifying to book his place in the tournament, closed with 11 straight pars as he moved one off the lead on two under.
The 43-year-old, who says he will "keep believing" he can win an Open, is joined on two under by fellow European Ryder Cup players Alex Noren and Nicolai Hojgaard and American Russell Henley.
Matt Wallace of England briefly led on four under after a birdie on the short eighth, but a wayward drive on the ninth led to a triple-bogey seven and he finished one under.
Scotland's Robert MacIntyre, who won last week's Scottish Open, opened with a one-over 72, one ahead of Spain's Jon Rahm and four better than England's Tommy Fleetwood.
World number one Scottie Scheffler and three-time Open champion Tiger Woods are among the later starters, with the weather forecast set for more of the same as the afternoon wears on.
McIlroy was moving along serenely at level par after his opening seven holes, a birdie on the third cancelling out a dropped shot on the first.
But the four-time major champion found trouble on Troon's two iconic holes.
His tee shot to the 118-yard par-three eighth 'Postage Stamp' landed on the green but trickled off right into a bunker and he took two to escape from the sand as he posted a five.
The Northern Irishman then sliced his tee shot on the par-four 11th 'Railway' on to the train track, as he carded a six on what has been the hardest hole in each of the past three Opens held here.
A run of three pars followed as he fought stay in the tournament but the emotion spilled out after he hit his second shot on the par-four 15th into one of Troon's many penal pot bunkers. He found another on the last. Both led to bogeys.
McIlroy came into this week on the back of a solid performance at last week's Scottish Open, where he finished joint fourth, but he is perhaps still bearing the scars of his collapse at last month's US Open, where he dropped three shots in the closing four holes to lose by one to Bryson DeChambeau.
American DeChambeau also failed to sparkle in the dreary conditions. He was five over after seven and he too found trouble at the eighth, where he dropped another shot.
"I could have thrown in the towel after nine and been like, I'm going home," he said.
"It's a difficult test, something I'm not familiar with. I can do it when it's warm and not windy."
The two-time major winner was seven over after bogeying the 15th but he was smiling after converting a 55-foot putt for eagle on the next as he ended on five over.
"I'm proud of the way I persevered. I've got a chance, I'm excited for the challenge," he added.
Thomas, who has won two US PGA Championship titles, rolled in four of his seven birdies on the front nine, one of which was on the eighth after coming within eight inches of holing his tee shot.
He overcame "a bit of a hiccup in the beginning of the back nine" when a wild drive on the 12th cost him two shots and another went on the next, but said he was rewarded for staying "patient" with his closing pair of birdies.
"Any time you can shoot under par, let alone in the 60s first round of a major - it’s great. It was tough out there," he told BBC Sport.
"There are a lot of variables that you can't control on links golf. I feel like over 72 holes, you're going to have some things not go the way you want and I’m just trying to stay as even keel as possible."