Golf: Third-round leader Graeme McDowell had it all to do again after three costly mistakes helped American David Toms into a two-stroke lead over Korean KJ Choi with nine holes to go in the Players Championship at Sawgrass.

After the bonus of a 50-foot birdie putt on the difficult fifth hole, Ireland's US Open champion carved his next shot into the trees.

Then, after bogeying that hole, he hooked his drive down the seventh into the lake and dropped another shot.

Worse was to come. Going for the green in two on the long ninth he hooked again into a small bush and, seeing no better option than to have a thrash at the ball, moved it only a few feet.

The next shot found rough and although he got up and down it meant a bogey six and an outward 38 that put him three behind with Nick Watney and Paul Goydos.

Toms, meanwhile, had three birdies in his first six holes, the last of them a pitch that finished just two inches from the cup.

The wonder at that point was how on earth the 2001 US PGA winner had gone over five years without a victory and had fallen to 75th in the world.

But he failed to get up and down from sand on the short eighth and missed a birdie chance at the ninth.

Watney posted a front nine 35 that promised so much more when he birdied the first three holes to reclaim a share of the lead.

Bogeys at the eighth and ninth hit his hopes of adding the title often dubbed the sport's unofficial fifth major to his Cadillac world championship in Miami in March.

Luke Donald, needing to win to take the world number one spot for the first time, managed only level par for the outward half and was four back.

He hit approaches to within two feet on the fourth and seventh, but they followed bogeys at the long second and sixth, where he raced a 22-foot birdie attempt nearly nine feet past.

McDowell and Donald, wearing navy blue in memory of the late Seve Ballesteros, were both trying to become the third European winner of golf's richest event - over £1million to the champion - in four years after Sergio Garcia in 2008 and Henrik Stenson 12 months later.

The day started with the completion of the third round and when McDowell birdied the 16th and 17th after two superb shots he was six under for the round and three clear.

But he had a bad break on the last when his approach kicked off the side of a mound across the green and into the lake for a double bogey six.

Choi hit a 177-yard second to two feet on the 10th, but then fell two behind Toms again by three-putting the next for a bogey six.

Donald also birdied the 10th from seven feet and he and McDowell, three behind, knew it could still be their day with so many nerve-testing holes to come.