David Duval's dreadful day at Royal Portrush was made worse after a score adjustment turned his 13 at the seventh hole to a nine-over-par 14.

The 2001 Open champion began this year's tournament with back-to-back birdies, but that was not at all a sign of things to come as he dropped four shots at the fifth.

Duval then endured a nightmare of scarcely believable proportions at hole seven, with a statement from Open officials detailing the events which led to the double-figure number that eventually adorned his card.

"David lost his first two balls from the tee and then played the wrong ball for the third ball played from the tee," the statement read.

"On discovering the mistake at the green he had to return to where the wrong ball was played, but the correct ball could not be found.

"Therefore he had to play again for the fourth time under penalty of stroke and distance. He played six shots in completing the hole with the fourth ball from the tee.

"He incurred a two-shot penalty for playing the wrong ball but the strokes played with the wrong ball do not count in his score."

The high farce ultimately contributed, quite substantially, to a first-round score of 91 - that is 20 over par.

Speaking when he thought he had scored a mere 90, the 47-year-old - who batted away a podium microphone in the mixed zone - said: "The description was like that tee shot didn't count as a stroke because it was a wrong ball, so there was a two-stroke penalty. It was the wrong ball.

"Everything after that is null. Doesn't matter. The next shots don't count anyways.

"Then up on the front of the green we discovered it was the wrong number two Titleist. So I'm at fault. I didn't take a close enough.

"You know what, there's a lot bigger things than this. And honestly, I stood here starting this week knowing that I'm playing really well.

"I figured if some good things happened I could run top 20. And obviously I'll be in last place."