Hilton Head - Luke Donald, set to become world No 1 with a victory, fired a one-under 70 to grab a one-shot lead over defending champion Jim Furyk after 54 holes of the Heritage tournament.
The Englishman strung together eight pars and a birdie at the par-4 16th on the back nine on Saturday to stand on 11-under par 202 after three rounds of the US PGA event, one stroke atop Furyk with Zimbabwe's Brendon de Jonge and American Scott Verplank two shots adrift.
Donald, currently ranked third, would move past current top man Martin Kaymer of Germany with a victory and also pass fellow Englishman Lee Westwood, who has won the Indonesian Masters.
Donald and Westwood traded "Good luck" messages on Twitter before their third rounds.
"I think I have an opportunity to go out there and win and if I do, I know what happens," Donald said. "It's just friendly banter."
Donald, who won the World Golf Championships Match Play title in February, took a double-bogey 7 on the second hole to stumble from the lead and just two holes later there were 17 players within two strokes of the top spot.
But Donald bounced back with birdies on the par-5 fifth for the third day in a row and the par-3 seventh for the second day in a row, then answered a bogey at the eighth with a birdie at nine to share the lead with Furyk.
The Englishman collected his last birdie of the day at 16, where he stuck his approach three feet from the pin.
But two par saves, at the third and fourth holes, were crucial, helping him rebound from the double-bogey at the second.
"Those up-and-downs and keeping some momentum going where I wasn't going completely backwards was big for me," he said
Australian Jason Day, playing for the first time since he shared second at the Masters, was in the hunt as well but began the back nine with three bogeys in a row to stumble back.
Furyk, twice a Heritage runner-up as well as last year's winner, suffered a 10-foot birdie lip out at 11 and faltered with a bogey at 12, but answered with birdies at 13 and 15.
Furyk found a sand trap on his approach at 18 and took a bogey to leave Donald on top.
"I've had a couple of good battles with guys down the stretch at this torunament and I look forward to another one tomorrow," Furyk said.
Furyk and Donald will be paired in Sunday's final group, renewing a rivalry that has seen some memorable tussles.
At last year's US PGA Tour Championship, Furyk saved par from a bunker on the 72nd hole to beat Donald by a stroke - winning the $10 million FedEx Cup bonus.
A week later Donald beat Furyk 1-up in Ryder Cup singles to contribute to Europe's victory.
The $5.7 million event is searching for a sponsor in order to return next year.
Donald has gone 118 holes without a 3-putt green, his last coming during the first round of the Masters.
Leading third round scores from the U.S. PGA Tour's Heritage Classic (par-71; U.S. unless stated)202 Luke Donald (Britain) 67 65 70 203 Jim Furyk 68 66 69 204 Brendon De Jonge (Zimbabwe) 67 71 66
Scott Verplank 67 70 67 205 Ricky Barnes 71 67 67
Tommy Gainey 71 67 67
Jason Day (Australia) 69 65 71 206 Pat Perez 71 67 68
Jason Dufner 67 71 68
Chris Couch 68 68 70
Ben Crane 69 66 71 207 Aaron Baddeley (Australia) 70 68 69
Tim Herron 65 71 71
Mark Wilson 66 70 71
Chad Campbell 65 69 73
Garrett Willis 64 69 74 208 Michael Bradley 71 71 66
Jeff Klauk 69 71 68
Matt Bettencourt 65 73 70
Spencer Levin 68 69 71
Nick O'Hern (Australia) 70 66 72
Brandt Snedeker 69 67 72
Camilo Villegas (Colombia) 66 68 74 209 Kevin Streelman 73 69 67
Carl Pettersson (Sweden) 71 69 69
Tim Petrovic 68 72 69
Bill Haas 70 70 69
Matt Kuchar 68 72 69
Stephen Ames (Canada) 72 68 69
Brian Gay 66 73 70
Boo Weekley 69 70 70
Paul Goydos 72 67 70
Blake Adams 67 71 71
J.P. Hayes 70 67 72
D.J. Trahan 69 67 73