Shanghai - America's Dustin Johnson will have to hold off a chasing pack containing the European Tour's finest players if he is to win the $8.5 million WGC-HSBC Champions after a birdie barrage on a spectacular on Saturday in Shanghai.
Johnson, despite two double bogeys on the back nine, shot a six-under par round of 66 to finish Saturday's third round on 18-under par 198 on a day when birdies flew in all over the course.
Johnson saw his five-shot overnight lead whittled down to three by Ryder Cup star and defending champion Ian Poulter, who shot a stunning nine-under par round of 63.
England's Poulter would have equalled the old course record, but Germany's Martin Kaymer had already lowered that mark to 62 earlier in the day to get to 10-under par after three rounds.
Four behind Johnson is former US Open champion Graeme McDowell who carded a 64. Two further back are former world number one Rory McIlroy (67), US Open champion Justin Rose (65) and Canada's Graham DeLaet (65).
"Doubling the last hole hurt a little bit," said Johnson, who took a seven at the par-five 18th after dumping his drive into water.
"But I played really good today. If you had told me this morning that I would shoot six-under I would have taken it."
Poulter said he would be aiming to go low again Sunday in pursuit of the mammoth winner's cheque of $1.4 million and hoped he could put some pressure on Johnson by playing alongside him in the final group.
"He's got a bit of a lead. It will be nice to keep an eye on him." said Poulter after his round. "Be nice to see if I can press if I need to press.
Poulter shot two 65s on the weekend to win this title a year ago at Mission Hills, Shenzhen. On Saturday he fired eight birdies, an eagle and a solitary bogey at 17.
"I've shot some low scores in Asia," added Poulter who in 2010 carded a 60 at the Hong Kong Open.
"If the conditions tomorrow are the same then guys are going to make a lot of birdies so I just have to attack and see what happens."
Northern Ireland's McDowell will complete the last group out on Sunday alongside Johnson and Poulter.
He lies second in the Race to Dubai European Tour standings with just two events left after this week and knows the importance of a good finish Sunday to close the gap on leader Henrik Stenson and keep daylight between those behind, England's Rose is in third place, even if a win eludes him.
"Dustin is doing what he need to do. It looks like Dustin is going to have to beat himself from here," said McDowell. "Race to Dubai points are very important to me. I have a lot to play for tomorrow. If not the trophy, certainly second place."
McIlroy has been back to near his very best this week. Apart from a stuttering back nine on Friday, he has been 15 under par for the other 45 holes at Sheshan Golf Club, and thinks a fast start on Sunday could put him in with a shout of the title.
"I need to get off to a faster start. I need to be two or three under through four or five holes because there's two good birdie chances on seven and eight," said the 24-year Northern Irishman. "There's definitely a very low score out there."
Earlier Kaymer shot a stunning 10-under-par 62 to beat the course he himself shared with four others.
The former US PGA champion began with an astonishing six birdies in his first seven holes to reach the turn in 30. He carded four more birdies on the back nine, but agonisingly missed a short putt at the ninth, his final hole, that would have equalled the lowest round of his career, a 61 at the Portugal Masters in 2007.
He beat the record 63 at Sheshan Golf Club that he had jointly held until Saturday with Johnson, McIlroy, Daisuke Maruyama and Ernie Els.
Leading scores on Saturday after the third round of the $8.5 million World Golf Championship-HSBC Champions at Sheshan Golf Club, Shanghai (par 72):
198 - Dustin Johnson (USA) 69-63-66
201 - Ian Poulter (ENG) 71-67-63
202 - Graeme McDowell (NIR) 69-69-64
204 - Graham DeLaet (CAN) 71-68-65, Justin Rose (ENG) 68-71-65, Rory McIlroy (NIR) 65-72-67
206 - Martin Kaymer (GER) 70-74-62, Boo Weekley (USA) 70-67-69, Bubba Watson (USA) 68-69-69
207 - Jamie Donaldson (WAL) 67-74-66, Keegan Bradley (USA) 71-68-68, Sergio Garcia (ESP) 70-68-69, Tommy Fleetwood (ENG) 68-70-69
208 - Gonzalo Fernandez-Castano (ESP) 67-71-70
209 - Scott Hend (AUS) 69-74-66, Jordan Spieth (USA) 68-71-70, Ernie Els (RSA) 69-69-71
210 - Bo van Pelt (USA) 77-67-66, Gregory Bourdy (FRA) 75-68-67, Louis Oosthuizen (RSA) 70-70-70, Jin Jeong (KOR) 70-69-71