Bubba Watson regained his composure after dropping three shots on the back nine holes to grab a one stroke lead after the third round of the Deutsche Bank Championship on Sunday.

The American made a birdie at the penultimate hole for a round of one-under-par 70 after losing his advantage with three bogeys between the 11th and 15th holes.

He finished the day on 11-under-par, one stroke clear of a group of five players, the two Australians Jason Day and Adam Scott, and three Americans, Jerry Kelly, Brendan Steele and Chez Reavie.

It's kind of like a box of chocolates. You never really know what you're going to get, Kelly said.

If we don't get any of that rain tomorrow, hopefully we don't, because I need the fairways to roll.

Britain's Luke Donald, the world's number one ranked player, and South Africa's Charl Schwartzel, the Masters champion, were among another bunch of five players at nine-under on a tightly congested leaderboard.

Watson, chasing his third win on the PGA Tour this season, threatened to open up a bigger lead when he made his fourth birdie of the day on the 10th hole to reach 13-under par, before he came unstuck.

He salvaged a birdie at the 17th to regain the outright lead but missed another opportunity when he only parred the par-5 18th as the chasers started closing on.

It started out with a bad shot on one and a quick bogey but I held it together, Watson said.

I fought down the stretch and I'm one up going into the last day so I have a good shot at it.

Scott, who shared the overnight lead with Watson and Schwartzel, birdied the last for a round of 71 while Day, who finished tied with his countryman in second place at Augusta in April, birdied the last two and made an eagle at the second in a round of 67.

It was hard to get the ball really close today, the greens were a little bit firmer, Scott said.

But I'm playing well, hitting the ball well. If I can do that tomorrow I should give myself a chance.

American Phil Mickelson carded the best round of the day, making six birdies and an eagle for a 63, to finish as one of two dozen players within four shots of the lead.

It was a good ball-striking round, one of the best I've had, Mickelson said.

The Deutsche Bank tournament is the second leg of the season-ending FedEx Cup playoffs.

The leading 70 players after Monday's final round move on to the BMW Championship in Illinois before the top 30 qualify for the Tour Championship finale at Atlanta.