Third-round leaderboard: -13 D Johnson (US) -11 L Donald (Eng), M Kuchar (US), N Watney (US) -10 R McIlroy (NI), H Mahan (US), A Scott (Aus), F Molinari (Ita) -9 P Harrington (Ire), M Laird (Sco)
Selected others: -6 P Casey (Eng), M Kaymer (Ger) -2 L Westwood (Eng), G McDowell (NI), T Woods (US) Level P Mickelson (US) +1 I Poulter (Eng) +2 J Rose (Eng) +5 R Davies (Wal), R Fisher (Eng)
Donald can go to number two in the world with victory at Doral
Luke Donald surged into contention with a 66 to trail leader Dustin Johnson by two shots going into the final round of the WGC Cadillac Championship.
The Englishman climbed into a tie for second on 11 under alongside Americans Matt Kuchar and Nick Watney as the big-hitting Johnson edged clear with a 65.
Rory McIlroy nudged to 10 under with Adam Scott and Francesco Molinari.
Ireland's Padraig Harrington and Scotland's Martin Laird were in a share of ninth at nine under.
World number one Martin Kaymer ended six under after a disappointing 74, while 14-time major champion Tiger Woods and world number two Lee Westwood were two under after rounds of 70.
Woods switched putters after his second-round 74, but though he improved he managed to hit only five fairways all day.
Northern Ireland's US Open champion Graeme McDowell was also two under following a round of 71 with Phil Mickelson (72) at level par.
Left-hander 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.
The 33-year-old Donald, who could climb one spot to number two in the world with victory at Doral on Sunday, had seven birdies, marred by a bogey at the last.
"I'm certainly playing very good golf right now, some of the best I've ever played," said Donald, who was never headed when he won the World Golf Championship (WGC) Match Play in Arizona last month.
He added later on
"Final pairing with Dustin tomorrow, should be a lot of fun. I'm really enjoying these World Golf Championships!!"
But it was Johnson who took control with another display of power hitting, taming the course known as the "Blue Monster" with eight birdies and a solitary bogey on the ninth.
Johnson, 26, has won four times on the PGA Tour but carded 82 as he blew a three-shot lead in the final round of the 2010 US Open and was controversially penalised two shots on the final hole of the US PGA to miss out on a play-off later that year.
"I finally feel comfortable with the putter, so things are going a little better," Johnson said.
Watney was tied with Johnson until hitting into the water on the 18th en route to a double bogey and a 68, while overnight leader Hunter Mahan's two closing bogeys for a 71 means he is now three back in joint fifth spot.