Michael Putnam, right, lines up his putt on the ninth green alongside Chad Collins during the final round of the Web.com Tour Mid-Atlantic Championship at TPC at Avenal. (Patrick McDermott/Getty Images)

Michael Putnam leaned back and kicked his leg in the air after his second shot on the par-4 sixth hole, body language that suggested his ball was in trouble as it headed for the green during Sunday’s final round of the Mid-Atlantic Championship at TPC Potomac at Avenel Farm. It was a misleading posture, because the ball landed softly about eight feet behind the hole.

That set up a crucial birdie, which came at a time when his closest challengers were crumbling. And it was a microcosm of Putnam’s approach on Sunday: He never let himself get too comfortable on the treacherous course.

Just a week after he won the Web.com Tour’s Mexico Championship, the 30-year-old Putnam shot a final round 68 to finish 7 under par and claim the Mid-Atlantic Championship — retaining his place as the highest-earning player on tour in 2013 and creating traction for a possible bid to the U.S. Open in two weeks. Putnam said he will play in Monday’s Open qualifying sectional at Woodmont Country Club in Rockville.

“I know that if I qualify for the U.S. Open, I’m playing great golf,” Putnam said. “This was a tough golf course that we played this week . . . if I could get in, I’d look forward to playing well.”

Raleigh, N.C., native Chesson Hadley finished second at 5 under after shooting a round of 67 and Australia’s Bronson La’Cassie finished third, 3 under for the tournament.

Officials at Avenel moved up Sunday’s itinerary due to possible afternoon thunderstorms, but the course was still hit hard by crosswinds. Putnam entered the day with a share of the lead with Chad Collins, who looked as if he was going to challenge Putnam all day after he holed in a lengthy chip shot on the third hole for birdie.

But as Collins was more erratic off the tee after that shot, bogeying the sixth, seventh, eighth and ninth holes, Putnam got stronger. He made birdies on three of the first six holes, including a putt on the sixth that stopped on the cusp of the hole before falling in, and he weathered the next seven holes with par putts.

“I knew holes 6 through 11 were going to be crucial because those were the holes that were into the wind,” said Putnam, a native of Tacoma, Wash. “If you get aggressive on this golf course, it’s really easy to make some bogeys. There’s penalties everywhere.”

Putnam said he “exhaled” on the eighth hole, when he hit his approach to four feet from the cup. He said at that point, he started to drift mentally— thinking about his family and what he was going to do with the $108,000 in winnings, and he missed the four-footer, which would have given him a five-stroke lead.

He promised not to exhale for the rest of the afternoon, and his play never wavered. Hadley made his run on the back nine, pulling within two of Putnam after birdies at 14 and 17 around a bogey on 15. Putnam noticed Hadley’s birdie on 17 on an electronic scoreboard before he tried his birdie putt at 16. He sank it, and Hadley knew he had come up short.

“Winning is extremely important . . . playing on the PGA Tour is more important,” Hadley said. “I was trying my hardest to win the golf tournament while maintaining second place. You always try to play to win. But perspective, big goal, big picture is we want to play on the PGA Tour.”