Published Sunday, 04 March 2012
Rory McIlroy of Northern Ireland hits out of the bunker on the 18th hole (© Getty)
The Holywood golfer finished joint best-of-the-day 66 on Saturday, taking him to 11 under par.
His two closest challengers are Americans Tom Gillis and Harris English.
England's Justin Rose had shared the halfway lead with Gillis, but had to settle for a one-over 71 that left him in joint fourth place and four behind.
McIlroy has to win on Sunday to dethrone Luke Donald at the top of the rankings.
The US Open champion missed a chance last week when he lost the final of the Accenture Match Play in Tucson to American Hunter Mahan.
Now, with Donald having a week off before returning for next week's world championship in Miami, McIlroy knows he has another golden opportunity.
This is where I want to be. This is why I play golf, to put myself in contention to win tournaments and try to become the best player in the world.
The 22-year-old hit back from a sticky patch midway through the front nine.
He had a hat-trick of birdies starting on the long third, two-putting there and then holing from 22 and 10 feet.
He was two clear at that point, but promptly bogeyed the next two, coming up short of the green on the sixth and three-putting the short seventh.
That gave Gillis the lead again and he stayed there with a remarkable run around the turn.
On the eighth he took a shoe and sock off and rolled up his trouser leg to play his ball out of the edge of the water and holed from 33 feet for par.
He followed that with a 28-footer for another par, birdied the 10th from five feet and then rescued a further par from 33 feet again on the next.
McIlroy had birdied the 11th from 45 feet after his approach from the rough only just carried over the lake and a glorious nine-iron to five feet at the 15th led to him regaining top spot on his own when Gillis failed to get up and down from sand there.
Bunkered in two at the par-five last, McIlroy splashed out 12 feet past the flag, but made it to complete the round.
Asked if he had learnt anything from last week McIlroy said: "It's a different format and the approach is slightly different.
"I didn't have as much time to think about it there because I went straight from the semi-final (a win over Lee Westwood) into the final.
"I've just got to try to approach it like any other tournament."
Meanwhile, Graeme McDowell's 69 put him in a share of 10th place, but he was seven back.
With the possibility of thunderstorms in the Palm Beach Gardens area on Sunday afternoon tournament organisers decided to move tee times forward.
McIlroy is due to tee off at 10.30am local time (15.30pm GMT) in a threeball with Gillis and English. Winds as high as 25mph are expected.