NORTON, Mass. — Paul Casey looked at the leaderboard late in the third round Sunday and saw a lot more names in the mix than he realized. He took care of that with a 3-iron within 30 inches on the final hole for an eagle and a three-shot lead at the Deutsche Bank Championship.

Then he looked at the forecast, and realized his work was just starting.

Casey made birdie and eagle over his last three holes for a 5-under 66, giving him a three-shot lead over Brian Harman going into the Labor Day finish as he tries to win on the PGA Tour for the first time in seven years.

Only five players were within five shots of Casey, who was at 15-under 198.

Rory McIlroy (66) and Louis Oosthuizen (64), who staged a duel at the TPC Boston four years ago, were six shots behind. It was difficult to count anyone out with a forecast of 35 mph wind and burst of showers from the remnants of Hermine due in New England.

Starting times have been moved forward to give the tournament the best chance of finishing.

“I don't think anyone's completely prepared for tomorrow,” Harman said after his 66. “It's more about survival and just doing the best you can.”

Harman will be in the final group with Casey and Smylie Kaufman (68), who was in the group at 11-under 202 along with PGA champion Jimmy Walker (70) and Kevin Chappell, who had the lead going into the back nine until hitting a tee shot into a divot that led to double bogey on No. 12. Chappell shot 71.

“To be sitting here at 66, I'm obviously over the moon,” Casey said. “Even with the great ball-striking, I found it difficult at the beginning, but to turn it around and have a lot of looks for birdies and make a few to come in, it's been great.”

Chappell, still looking for his first PGA Tour victory, made a birdie at the 10th to get to 13 under until he went at the flag from the divot in the 12th fairway. He came up short in the hazard, tried to play out of the native scrub and went over the green and wound up with a double bogey.

“I said yesterday that at some point in time during the next 36 holes, I was going to be hit with adversity,” Chappell said. “Felt like I hung in there and finished with six straight pars from not-the-best position. So that's what I'm going to choose to look at, and hopefully tomorrow I can get the ball in position and try to make some birdies.”

Casey made his at the right time, and his eagle at the 18th sent him home with a smile.

He had 232 yards to the hole with the wind coming in and out from the left. The wind picked up and his caddie, John McLaren, stepped in and called him off. The wind died slightly, and the fun wasn't over.

“It looked left,” Casey said about his shot. “And then the wind gusted and it went right. And after that, I was happy it got over.”