AUGUSTA, Georgia, April 7 (Reuters) - A frustrated Luke

Donald blew his chances of contending for the Masters after

dropping five shots on the tricky back nine in Saturday's third

round at Augusta National.

The British world number one, among the favourites for the

year's first major, had made a sizzling start with an eagle at

the par-four third but then struggled over the closing holes to

card a three-over-par 75.

Donald, who had won his final tournament before the Masters

with a victory at the PGA Tour's Transitions Championship,

limped home in five-over 41 to post a seven-over total of 223.

"There is nothing worse than waking up on Sunday knowing

that, whatever you do, it is not going to be good enough," the

Englishman told reporters after ending up 12 strokes off the

early third-round lead.

"It's difficult," Donald said of his messy finish to the

round which included a double-bogey seven at the 13th where he

dumped his second shot into Rae's Creek.

"You feel like you have lost your ability to contend on

Sunday which is the goal at the majors, to have a chance. But I

will always keep trying my hardest until the very end and

tomorrow will be no different."

Though Donald has yet to win a major title, he has become

one of the most consistent players of his generation and last

year became the first golfer to win the money list titles on

both sides of the Atlantic.

Renowned for a superb short game that should give him an

edge on the heavily contoured and slick greens at Augusta

National, the Briton felt he had played better on Saturday than

his scoring suggested.

"I had a three-iron into 13 and thought I hit a decent shot

but missed carrying (the water) by two inches, otherwise I would

have been 30 feet for eagle," Donald said. "But I made seven.

"That's how this course is sometimes. Same on 14. I drilled

a five-iron right of the pin and if it goes another three or

four feet I have a 10-footer for birdie. It rolls down the hill

45 feet away and I three-putt.

"I was playing fine. It's just been one of those weeks."

Donald's brightest moment of the day came at the third where

he holed out from the fairway with a lob wedge.

"I had 80 yards and spun it back down the hill perfectly

into the hole," he said. "At that point I'm seven behind with

great conditions and perfect greens.

"If I can just make four more birdies, I'm two or three

under for the tournament and who knows.

"I've not played that badly. I've probably driven it as well

as I ever have around here. My iron play hasn't been sharp

enough and certainly not my short game."

Donald's best Masters finish came on his debut in 2005 when

he tied for third after shooting successive 69s over the

weekend.

(Reporting by Mark Lamport-Stokes; Editing by Frank Pingue)