The American this year won the US PGA Championship and became the first golfer since 1989 to clinch back-to-back US Open titles.

Koepka, 28, won the award ahead of Dustin Johnson, Bryson DeChambeau, Open champion Francesco Molinari, Justin Rose and Justin Thomas.

PGA Tour members who have played in at least 15 FedEx Cup events in the 2017-18 season were eligible to vote.

Rumours of an argument between Koepka and world number one Johnson at the Ryder Cup, which were denied at the time, have since been confirmed by US captain Jim Furyk.

"Whatever altercation started, or what happened, it was very brief," Furyk said. "They're like brothers. Brothers may argue, brothers get into it. But they're as close as they've ever been, and it really had no effect on either one of them."

There appeared to be no remaining ill-will between the pair, with Johnson tweeting his congratulations to his US Ryder Cup team-mate.

An incident at the Ryder Cup left Koepka "heartbroken" after his tee shot resulted in a spectator losing sight in her eye.