DORAL, Florida: American Dustin Johnson held a two-stroke lead over a trio of challengers, including Britain's Luke Donald, after the third round of the WGC-Cadillac Championship Saturday. Johnson, whose seven-under-par 65 on the Blue Monster course at Doral was the day's best score, is 13-under par overall with Donald and Americans Matt Kuchar and Nick Watney a further two shots back. Watney and Donald both struggled on a difficult final hole where a number of balls dropped in the water on the left side. Watney, who began his round with an eagle on the first, found the water and double-bogeyed the 18th while Donald's drive was caught by the wind and went wide into the rough on the right as he bogeyed. Johnson, a four-time PGA Tour winner, ended his round in style with birdies on the 16th and 17th. “It's going to take another good round. I played well today, drove it well, putt it well and I am going to have to do that again,” Johnson told reporters. Sunday's final round is wide open though as 12 players are withing five shots of the overall lead. The chasing dozen includes Northern Ireland's Rory McIlroy, Italian Francesco Molinari, Australian Adam Scott, Ireland's Padraig Harrington, Scotsman Martin Laird, Dane Anders Hansen and Fijian Vijay Singh. But the player who Johnson will likely be most worried about is Englishman Donald, who shot a six-under-par 66 as he searches for his second World Golf Championship win of the season following his triumph in the WGC-Accenture Match Play Championship in Arizona last month. Donald said he was in his most consistent form in five years. “My swing is technically sounder and I am feeling more and more comfortable on certain shots which I didn't last year and obviously the results are showing that,” he said. Donald is seeking to join Tiger Woods as the only players to win back-to-back WGC events. Struggling Woods shot a two-under-par 70 but is 11 shots off the lead, tied in 30th place. But he may take some comfort in being two strokes better than playing partner Phil Mickelson. Mickelson, ranked sixth, will overtake fifth-placed Woods in the world rankings for the first time in 13 years if he finishes two strokes better than his rival.