The Open: David Duval says he'll finish last after posting worst score since 1997

David Duval's opening-round score was later amended to 20 over

Former champion David Duval said he was resigned to finishing last at The Open at Royal Portrush after posting a 20-over-par 91 - the tournament's worst round in 22 years.

His calamitous round included a 14 on the par-five seventh where he incurred a two-shot penalty for hitting the wrong ball before he produced a triple bogey on the 17th.

"I thought this week if some things happen I could make top 20," he said.

"Obviously I'll be in last place."

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He added: "I've just done something I've never done as a professional. I've posted 85 twice, but I've never posted a 90. It was a long day, a rough day."

The 47-year-old is currently ranked 2,080 in the world with various injury issues having affected him since he won the 2001 championship at Royal Lytham.

On his seventh hole nightmare, he said: "I had a couple of bad tee shots and then we thought the marshal had my ball, asked if it was a Titleist 2, I looked at it and saw a two and played almost the entirety of the hole and it turns out with the wrong ball.

"There was a two-shot penalty for the wrong ball and then I had to go back to the tee and basically start the hole over. A very unique, awful situation."

Duval's score on the hole was originally given as a 15 before it was rounded down to 13 and then back up to 14. Duval believed he had shot 90 and signed his card accordingly, but more than an hour and a half later his score was amended by officials without further penalty.

Duval, who carded 80 in his opening round at Carnoustie last year before withdrawing, defended his decision to keep returning for the tournament despite his low ranking.

"It's not reflective of anything I've been doing it's just one of those awful nightmare scenarios," he added.

The previous worst Open round was Ian Baker-Finch's 92 in the first round at Troon in 1997 while the worst-ever round was Guy McQuitty's first-round 25 over-par in 1986.

Duval's 14 on the par-five seventh was the highest score on an Open hole since Hermann Tissies' 15 on the eighth at Troon in 1950.