Mass -  Australian Jason Day continued his emergence as one of the game's best young players when he earned a one-stroke lead after the third round at the $7.5m Deutsche Bank Championship on Sunday.

Day, who began the round tied for the lead, made a tap-in birdie at the par-five 18th for a five-under-par 66 that included just one bogey, a three-putt blemish at the 16th hole at the Boston TPC.

"I played great today. I made a hiccup on 16, but overall very happy to be where I am right now," said Day, who was at 17-under 196.

American Brandt Snedeker (67) was alone in second place on 16-under after chipping in to salvage par at the last, where he hit his second shot into a hazard.

Briton Luke Donald was two strokes behind, while defending champion Steve Stricker, without a bogey all week, trailed by four with fellow American Charley Hoffman.

Day is often overlooked amid talk of who might be the next great player, but his credentials the past few months are impressive.

The 22-year-old has not missed a cut since clinching his maiden PGA Tour victory at the Byron Nelson Championship in May, and just last month was in contention during the final round at the PGA Championship, where he finished tied for 10th.

"The biggest thing for me tomorrow is to commit to the shot that needs to be hit, just keep hanging around and try and make them chase me," Day continued.

"I just have to look away from the leader boards and keep giving it 100 percent and keep playing my game."

Snedeker played down the importance of his splendid par-save, a 40-foot chip-in at the last.

"A two-shot lead really isn't that much difference between a one-shot lead," said Snedeker.

"Jason played fantastic today. I don't see him slipping tomorrow, so I'm going to have to shoot something low. Luckily I didn't fall too far behind today.

"I struggled with the tee ball but my short game was fantastic. I chipped in a couple of times and made some key putts to keep it going."

Third-place Donald, buoyed by his selection last week on the European Ryder Cup team, is feeling relaxed.

"There was some relief (getting a captain's pick) and now I'm just enjoying being out here," he said. "I struck the ball much better than the first two days and putted nicely on the back nine."

World number one Tiger Woods will go another week without winning, despite a respectable two-under 69. He started the day seven strokes from the lead but ended it 10 behind.

"Today was a bit of a struggle," said Woods, who has not won this year while going through divorce in the wake of revelations of marriage infidelity.

Barring a poor final round, he should be among the 70 players who advance to next week's BMW Championship, the third of four events in the PGA Tour's FedEx Cup playoff series.

Leading third round scores on Sunday from the $7.5 million Deutsche Bank Championship (USA unless noted):

196 - Jason Day (AUS) 63-67-66

197 - Brandt Snedeker 66-64-67

198 - Luke Donald (GBR) 65-67-66

200 - Steve Stricker 65-68-67, Charley Hoffman 64-67-69

201 - Geoff Ogilvy (AUS) 64-72-65, Adam Scott (AUS) 67-69-65, Phil Mickelson 69-65-67, Charlie Wi (KOR) 68-66-67

202 - Justin Leonard 69-66-67, Andres Romero (ARG) 68-66-68, DJ Trahan 64-69-69

203 - John Senden (AUS) 66-68-69, Vijay Singh (FIJ) 66-68-69, Tom Gillis 67-71-65, John Rollins 66-70-67, Matt Kuchar 66-65-72

Notable others:

205 - Yang Yong-Eun (KOR) 67-70-68

206 - Brian Davis (GBR) 64-73-69, Tiger Woods 72-65-69, Angel Cabrera (ARG) 69-68-69, Michael Sim (AUS) 68-66-72

207 - Ernie Els (RSA) 70-67-70, Retief Goosen (RSA) 67-69-71

208 - Matt Jones (AUS) 65-70-73

209 - Rory McIlroy (NIR) 64-76-69, Martin Laird (GBR) 66-69-74, Paul Casey (GBR) 66-72-71

210 - Fredrik Jacobson (SWE) 65-76-69, Camilo Villegas (COL) 67-72-71, Stephen Ames (CAN) 67-68-75

211 - Ryuji Imada (JPN) 67-71-73

212 - Greg Chalmers (AUS) 68-72-72, KJ Choi (KOR) 69-71-72, Tim Clark (RSA) 69-72-71, Brendon de Jonge (ZIM) 67-72-73

213 - Stuart Appleby (AUS) 70-71-72, Ian Poulter (GBR) 67-73-73

214 - Robert Allenby (AUS) 69-70-75

216 - Marc Leishman (AUS) 71-68-77, Aaron Baddeley (AUS) 71-70-75