Los Angeles - Rory McIlroy birdied the last three holes, closing with a dramatic 27-foot putt, to seize a one-stroke lead over top-ranked Brooks Koepka after Saturday's third round of the WGC St. Jude Invitational.
The four-time major winner from Northern Ireland fired an eight-under par 62 to stand on 12-under 198 after 54 holes at par-70 TPC Southwind in Memphis, Tennessee.
"To birdie the last three holes and take the lead puts me in a really great position going into tomorrow," McIlroy said. "I've holed a lot of putts this week, which is nice."
Third-ranked McIlroy's second-lowest round of the season, eclipsed only by a 61 in the final round of his Canadian Open triumph last month, comes a week after a disappointing missed cut at the British Open at Royal Portrush in Northern Ireland.
It also booked the 30-year-old a first-ever Sunday pairing with four-time major winner Koepka in the last group for the final round of the elite World Golf Championship event.
"Rory is playing with some heat," Koepka said. "I'm just going to have to take it deep."
England's Matthew Fitzgerald fired a 69 to stand third on 200, one stroke ahead of Spain's Jon Rahm, Sweden's Alex Noren and Australian Marc Leishman.
McIlroy birdied the last three holes on both the front and back nine.
"I had a lot of good numbers where I could make a full committed swing," McIlroy said. "One of my goals was to hit it pin high and I did that for most of the day."
McIlroy sank a six-foot birdie putt on the opening hole and dropped one that was half as long at the third, then reeled off a 23-foot birdie putt at seven and back-to-back seven-footers for birdies at the par-3 eighth and par-4 ninth.
After finding water off the 12th tee and taking his lone bogey of the day, McIlroy answered by dropping his tee shot to five feet at the par-3 14th and sinking the birdie putt.
McIlroy then closed with a six-foot birdie at the par-5 16th, a 16-footer at 17 and his dramatic long birdie effort at 18.
"I just put it a little outside right and it went in, which is nice," McIlroy said of his final putt.
Koepka, who defended a major title at this year's PGA Championship, saw his ball cling to a slope on the rough over greenside water at 18 but got up and down for par to close on 64.
"I saw some putts go in and that's always nice," Koepka said. "The holes seemed to open up for me today."
Koepka, who has never won a WGC title, could become only the fourth player to win WGC and major events in the same year.
"Every time I tee it up I feel like I have a chance to make some history," he said. "I'm enjoying it while it lasts."
Overnight leader Fitzpatrick had six birdies, three bogeys and a double bogey in a roller-coaster round as the five-time European Tour winner chases his first US PGA triumph.
A victory would see the 24-year-old Englishman book a place in the US PGA Tour's season-ending playoffs.
Fitzpatrick sank an 18-foot birdie putt at the par-3 11th to seize a one-stroke lead, but sent his next shot off the 12th tee into the water on the way to a double bogey that dropped him behind Koepka and McIlroy.
He followed with bogeys at 13 and 15 but answered with birdies at 16 and 17 to stay on the leaders' heels.
Leishman fired a 63 with an eagle and three birdies over the last five holes. The Aussie sank a 12-foot birdie putt at 14, holed out from 43 feet from the rough at the par-5 16th and closed with back-to-back birdie putts from just over three feet.
198 - Rory McIlroy (NIR) 69-67-62
199 - Brooks Koepka 68-67-64
200 - Matthew Fitzpatrick (ENG) 67-64-69
201 - Marc Leishman (AUS) 69-69-63, Alex Noren (SWE) 66-69-66, Jon Rahm (ESP) 62-71-68
202 - Thorbjorn Olesen (DEN) 66-71-65, Ian Poulter (ENG) 66-69-67, Billy Horschel 67-66-69