SHEFFIELD'S Danny Willett faces the difficult task of clawing back a five-shot deficit on four-time major champion Rory McIlroy if he is to win the WGC-Cadillac Championship at Doral.
Willett shot a third-round 72 after shackling himself with a double-bogey six at the 436-yard par-4 third.
A further shot was dropped at eight, but the Yorkshireman - winner last month of the Omega Dubai Desert Classic - responded with four birdies in the next six holes.
Another birdie followed at the 16th, but it was sandwiched by bogeys at 14 and the last.
McIlroy's new putting technique continued to pay dividends as the world No 3 added a 68 to his opening scores of 71 and 65 to lead by three from American Dustin Johnson (71) and Australian Adam Scott (73).
Willett (68 69 72), who is in a tie for fourth place with two former Masters champions in Phil Mickelson and Bubba Watson, said: “It was not the best start in the world. It was a little bit of a scrappy day, but I’m five back.
"It was just a bit of a shame to drop one on the last. I’m seven under par going into Sunday, so it’s all to play for.
“Saturday was pretty tricky. Rory's score out there, is a very, very good score . It depends how they set the golf course up (on Sunday) and what the weather does, but I think it's Rory's to lose really. I’m going to have to go out there and play clever and play aggressive when I can, and hopefully I can knock a few birdies off and post a good number.”
Willett's fellow Sheffielder Matt Fitzpatrick is in a tie for 41st as he seeks his first sub-70 round of the tournament (76 71 72).
After dropping shots at the second and fourth holes, the British Masters champion eagled the 549-yard par-5 eighth and went four under par for as many holes by also birdieing 10 and 11.
However, he dropped shots at 14 and 16 to dip back to level par for the day and three over for the tournament.
McIlroy had finished third, sixth and 20th in his first three events of 2016 before a missed cut in the Honda Classic last week prompted him to switch to a "crosshanded" putting method he last used in 2008.
The 26-year-old needed 33 putts in his opening 71, but just 25 on Friday and carried on where he left off on Saturday, taking 28 putts in a 68 which was the joint second lowest score of the day.
That meant McIlroy turned a two-shot deficit to a three-shot lead over defending champion Johnson and halfway leader Scott.
McIlroy got up and down from a greenside bunker to birdie the par-5 first and picked up another shot from seven feet on the fifth, before a birdie on the eighth - despite finding two bunkers - took him into the outright lead for the first time.
Scott had bogeyed the difficult fourth and missed from nine feet for eagle on the eighth, although the tap-in birdie meant he trailed playing partner McIlroy by a single shot as he looked to claim back-to-back wins following his victory in the Honda Classic.
McIlroy extended his lead with a birdie on the 10th and when Scott bogeyed the 13th after failing to get up and down from a greenside bunker, the Northern Irishman was three shots clear.
Scott responded with one of the shots of the week on the 14th, his recovery from a fairway bunker catching the edge of the trap but still finishing just nine feet from the hole.
The former Masters champion duly converted for birdie and was joined on 10 under by Johnson, who had picked up a shot on the short par-4 16th.
However, Johnson then bogeyed the last after a wayward drive and Scott did likewise on the 17th, meaning McIlroy's par save from a greenside bunker on the last put him firmly in pole position in pursuit of a third WGC title.
Sergio Garcia, who was second to Scott at the Honda Classic, fellow Spaniard Rafael Cabrera-Bello and India's Anirban Lahiri afe all seven shots back.
McIlroy said: "That's my first bogey-free round of the year and to do it in a round like this is very pleasing. I've been saying all week that I've been making the birdies and I've been hitting the good shots, I've just been making too many mistakes.
“To play the last 36 holes on a golf course like this with just one bogey on the card is really what I wanted to achieve this week. I feel really good about my game.
"My ball-striking, tee-to-green, my driving, that really hasn't been an issue this year. That's been where I wanted it to be. But my scrambling and my putting have needed work.
"I feel like the practice that I've put in over the last few weeks is really starting to pay off. Just look at some of the saves I had out there on Saturday and some of the big par putts - those were the things that were missing over the past three or four tournaments. And to be able to correct that and go out and play in a final group on a Saturday in a golf tournament like this, on a golf course like this, and play bogey-free, it gives me a lot of confidence going forward.”