After the thrill of pitching in for an eagle two on the third and thinking he could climb back into contention, Donald wrote off his chance after going in Rae's Creek on the 13th and running up his second seven of the week.

"There's nothing worse than waking up on a Sunday and whatever you do is not going to be good enough," the 34-year-old said as he dropped outside the top 50 on seven over par.

Even if Donald climbs around 10 places in the final round, Rory McIlroy, one off the lead at halfway, would only need to finish 20th to take back the number one spot.world

There is also the possibility of Lee Westwood regaining the position he last held in May, before Donald beat him in a play-off for the BMW PGA Championship at Wentworth.

Westwood needs win his first major title to have a chance of leapfrogging over Donald and McIlroy.

Donald's chance effectively ended when his second shot found the water at 13. "I thought I hit a decent shot," Donald said of his three-iron, "but it missed carrying by two inches."

After a penalty drop he skimmed his pitch over the green and three-putted - as he did on the 14th. Missed putts of six feet on the 16th and 18th just piled on the agony.

"I had high hopes for this week," he added. "I will think about my build-up, but I felt ready. At least I won some crystal for the eagle, that's about the only high."