The 2013 winner, boosted by an early eagle, posted a 13-under 200 total with one round remaining at TPC Boston in Massachusetts.

American Fowler (67) made a good par-saving putt at the last to trail by one stroke, with Australian Matt Jones (68) and American Sean O'Hair (67) two behind.

Stenson's bogey-free round included an eagle at the short par-four fourth hole, where he drove the green and sank a slippery downhill 20-foot putt.

"That was the highlight of the day," said the three-time member of the European Ryder Cup team.

"I'm just going to try and do more of the same, pick my targets, hit my shots and commit on my putts. It's worked out so far and I'll try to do the same tomorrow."

Stenson is seeking his fifth PGA Tour win and first since he capped off his brilliant 2013 FedExCup playoff run with a win at the Tour Championship.

The 39-year-old, ranked eighth in the world, began the playoffs last week with a runner-up finish at The Barclays.

"There are a few of the guys at the top of the leaderboard who want to win and I'm happy to be in the mix," Stenson said.

He will play in the final pairing on Monday with Fowler, who won the Players Championship and Scottish Open earlier this season.

Fowler failed to hit a fairway on his front nine, but still managed to find every green in regulation.

"I actually was making some good swings, I just wasn't hitting the ball in the center of the face," Fowler said.

"I was really trying to get the most out of the round and I was trying to think through every shot."

Meanwhile, PGA Championship winner Jason Day's stretch of 22 consecutive rounds of par or better, the longest streak on the PGA Tour this year, ended when the Australian stumbled to a 73.

Second-round leader Charley Hoffman also struggled. He tweaked his back early in the round, shot 76, and fell six strokes behind. Fellow American Hunter Mahan (64) was also six back after the best round of the day.

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