(CNN) - Golf is hard.
And as if to prove the point, David Duval and Rory McIlroy both showed that even past Open champions can be made to look like weekend hackers.
Duval, the winner in 2001, notched up a sizeable 14 on the seventh hole, while 2014 champion McIlroy opened with a four-over-par eight at the first on day one of the 148th Open Championship.
For McIlroy, that certainly wasn't in the script.
The local hero was supposed to take the Open by storm at Royal Portrush.
He was roared onto the first tee by an adoring public as one of the hot favorites to win as the Open returned to Northern Ireland for the first time in 68 years. What a fairy tale it would be.
Except that he made a horror start as he carved his drive left into out-of-bounds and was forced to hit a second tee shot, which found deep rough.
The four-time major champion's stomach must have been churning as the cushion of confidence and expectation collapsed from under him.
The heaving crowds lining the fairway and packed in around the hilltop green were stunned, too. The weather, blustery but dry, wasn't even to blame.
From there, McIlroy hacked up short of the green but found more long grass, from which he had to take a penalty drop. He finally found the green for six and took two putts for an eight -- what's known in golf as a "snowman."
McIlroy was wayward again off the second tee and dropped another shot with a fluffed chip at the short third before steadying his ship.
'I let myself down'
Two birdies took him to the turn just three over, but McIlroy dropped five shots in his last three holes to finish the first day with a 79 for eight over par.
"I would like to punch myself," he told BBC Radio 5 Live. "I made a couple of stupid mistakes. I was pretty nervous on the first tee and hit a bad shot."
He continued: "At the end of the day, I play golf to fulfil my ambitions, not anyone else's, but I wish I could have given the crowd something to cheer about.
"I let myself down more than anyone else and need to pick myself back up."
By day's end he trailed first-round leader JB Holmes by 13 shots.
In a neat link-up, McIlroy met Duval -- playing in the group in front -- when the American hitched a buggy ride back to the tee on the seventh as McIlroy's group waited to play.
The 47-year-old Duval, a former world No.1 and Tiger Woods' chief nemesis for a spell, doesn't play much these days. The last of his 13 Tour titles came with that Open victory at Royal Lytham, and after injuries and a period away from the game he is more accustomed to the TV golf analyst's chair.
He may wish he had stayed there.
Duval had started with two birdies but made his own eight at the fifth after losing two balls, and then outdid that in spectacular fashion at the long seventh.
He lost his first two balls from the tee and then played a wrong ball from the third ball hit. He discovered the mistake at the green, which meant he had to return to where the wrong ball was played.
But he couldn't find the correct ball and had to go back to the tee again -- where he encountered McIlroy, Paul Casey and Gary Woodland. He took six shots to complete the hole with the fourth ball hit, and including a two-shot penalty for playing the wrong ball, his score added up to 14. It was originally recorded as 15, then corrected to 13 on the official leaderboard, before a final statement from Open organizer the R&A settled on 14.
"Very unique, an awful situation," Duval told reporters afterward. "I'm at fault, I didn't take a close enough look [at the ball.]
"It was fairly unsettling, obviously. I came here with fairly high hopes. I've been playing well."
Duval has been hampered by injuries throughout his career, and admitted the tendonitis in his left arm "hurts like crap."
But he was adamant the right thing to do was continue playing. "You have an obligation as a professional athlete, if you play, you post your score. Is there some, I don't know, embarrassment to it? I don't know, but I teed off in the Open and I shot 90 [corrected to 91] so put it on the board."
It was the highest score on an individual hole at the Open since Herman Tissie made 15 at the Postage Stamp eighth at Royal Troon in 1950.
The seventh is one of two new holes -- along with the eighth -- at Royal Portrush for the 2019 Open and Duval has written a dramatic first chapter in its history.
Things didn't get better for the Duval who finished with a 91 for an astonishing 20 over.