Adam Scott, who won his first major title at The Masters, fired a five-under par 66 on Sunday to capture The Barclays, the first leg of the PGA Tour playoffs.

The Australian took the early clubhouse lead by posting a bogey-free round to reach 11-under par 273 and then watched a number of challengers fall short, including a hurting Tiger Woods, who finished in a tie for second.

"I can't believe it," said the 33-year-old Scott from Adelaide. "I just played a good round today. Things turned my way a lot out there."

Woods, battling back pain, ended up in a tie with three others after shooting a two-under 69 at Liberty National Golf Club. Woods' attempted birdie putt on 18, which would have put him in a playoff, stopped just inches short of the cup.

Canada's Graham DeLaet (65), England's US Open champion Justin Rose (68) and third round co-leader Gary Woodland (73) were level with Woods at 10-under 274.

Scott got his US PGA playoff series off to a successful start as he claimed his first title since his triumph at Augusta National.

He denied world No 1 Woods a chance to win his sixth tournament of the year.

Scott, whose anchored putting style will be banned starting in 2016, caught fire in the middle of his front nine with three-consecutive birdies beginning at the par-four fifth.

England's Rose, Woods and Woodland all had a chance to force a playoff at the 18th hole, but none of them could make birdie.

Woods came the closest but his long putt from off the green did a double curl and stopped just shy of the hole.

"I hit good putt and I thought I made it," said Woods, who battled through back spasms all weekend long.

The spasms became so bad on the back nine on Sunday that Woods grimaced and dropped to all fours after hitting one shot on the 13th fairway. The shot sailed left and into a water hazard that resembled a sea of green muck, forcing him to take a drop.

"I had back spasms big time," Woods said. "It started a little before but 13 accentuated it."

The Barclays is the first leg of the USPGA Tour's playoffs which continue in Boston this week with the Deutsche Bank Championships. The top 100 in the playoff points standings advance to the Deutsche Bank.

Seventy will then advance to the BMW Championship, and the series culminates with the top 30 players in the standings competing in the Tour Championship, with the points leader at the end earning a $10 million bonus.