Unheralded American Brian Harman won his first PGA title on Sunday, capturing the John Deere Classic to claim a spot in next week’s British Open.

Harman became the 20th player to win his first US tour crown at the $US4.7 million ($A5 million) event, firing a final-round five-under par 66, to finish 72 holes on 22-under 262.

Zach Johnson, the 2007 Masters champion and a home-area hero who won the event in 2012, settled for his third runner-up showing in the event on 263.

Queenslander Steven Bowditch was the best of the Australians in a share of 11th, seven shots off the lead.

Harman, who matched his best prior US PGA finish with a third-place effort at Riviera in February, had missed the cut the past two weeks but took home the top prize of $846,000 at Deere Run.

The victory qualified Harman for the British Open at Royal Liverpool, which starts Thursday in Hoylake, England.

“I brought my passport and a couple of jackets,” Harman said. “I can’t wait to get on that plane.”

Harman eagled the par-5 second after putting his approach four feet from the cup, took a bogey at the fifth but responded with a 30-foot birdie putt at the ninth and added a 16-foot birdie putt at the par-5 10th.

Johnson kept the pressure on Harman with a bogey-free round of 64 that included birdies at 13, 14 and 17 to stay on the leader’s heels.

But Harman answered the challenge with three birdies in a row starting with an eight-foot birdie putt at the 14th followed by a 15-foot birdie putt at 15 and a six-footer at the par-3 16th.

That allowed Harman to par the 17th and bogey 18 for the victory.