Hilton Head - World No 1 Dustin Johnson, seeking his third victory of the year, fired a three-under par 68 to grab a one-stroke lead after Saturday's third round of the PGA Tour's Heritage tournament.

Johnson, who shared second in last week's Masters at nearby Augusta National, stood on 10-under 203 after 54 holes at Harbour Town in Hilton Head, South Carolina.

The 34-year-old American, a native of state capitol Columbia, won a European Tour event in Saudi Arabia and the WGC Mexico Championship in February but hopes to capture his 21st PGA title in his home state.

"It would be special," Johnson said.

"But there are a lot of guys around. I'm going to have to play really special tomorrow if I want to win."

One stroke adrift were England's Ian Poulter, Slovakia's Rory Sabbatini and Ireland's Shane Lowry, while Americans Patrick Cantlay, Scott Piercy and Trey Mullinax, Taiwan's Pan S.T., South Korean K.J. Choi and Argentina's Emiliano Grillo shared fifth on 205.

Lowry led after the second round was concluded early on Saturday due to storms that interrupted play on Friday, and he stretched the margin to three shots with birdies at the par-5 second and fifth holes and another from 33 feet to close the front nine and stand on 12-under.

But Lowry found two bunkers at the par-4 13th, water at the par-3 14th and more sand on the par-4 16th on the way to bogeys on each hole that dropped him back as Johnson charged.

Johnson, who moved back atop the rankings after losing the No 1 spot to England's Justin Rose last week, sank an eight-foot birdie putt at the second and holed a 19-footer for birdie at the par-4 sixth.

"I feel like I've been driving it well," Johnson said.

"That's a big key around here."

After answering a bogey at the eighth with a tap-in birdie at the par-4 ninth, Johnson made a crucial par save at the par-4 12th, his tee shot well right of the fairway but a 12-foot par foot rescuing him.

"That was a really nice save," Johnson said.

"That was one of my bad tee shots."

Johnson followed with an 18-foot birdie putt at the par-4 13th, then holed a 47-footer for birdie at the par-3 14th.

"I was definitely surprised," Johnson said of his long birdie putt.

"I just laughed."

Johnson was smiling again at the par-5 15th, where he went into a greenside bunker with his second shot but blasted out to 13 feet and sank his birdie putt to seize the lead alone.

But Johnson missed the green on the par-4 16th and par-3 17th on his way to bogeys, missing par putts from nine and five feet respectively.

"The course played very difficult, especially the last three holes with the wind direction we had," Johnson said.

"I hit good putts on 16 and 17 that ended up being bogeys."

Scores after Saturday's third round of the PGA Tour's Heritage (Par 72, USA unless stated):

203 - Dustin Johnson 68-67-68

204 - Ian Poulter (ENG) 70-67-67, Rory Sabbatini (SVK) 67-69-68, Shane Lowry (IRL) 65-68-71

205 - Patrick Cantlay 67-72-66, Scott Piercy 67-70-68, Pan CT (TPE) 71-65-69, KJ Choi (KOR) 70-66-69, Trey Mullinax 66-68-71, Emiliano Grillo (ARG) 68-67-70

206 - Matt Kuchar 69-69-68, Sam Burns 67-70-69

207 - JJ Spaun 70-69-68, Kevin Streelman 69-69-69, Chez Reavie 68-71-68, Rafa Cabrera Bello (ESP) 68-69-70, Charley Hoffman 68-69-70, Daniel Berger 66-69-72, Webb Simpson 69-73-65

208 - Michael Thompson 68-71-69, Seamus Power (IRL) 68-72-68, Eddie Pepperell (ENG) 71-69-68, Peter Malnati 67-72-69, Alex Noren (SWE) 67-74-67, Denny McCarthy 70-68-70, Troy Merritt 69-67-72