After opening the door for Rahm by shooting two over par for his first nine, Scheffler, posted birdies on the 10th, 14th and 15th to re-establish a buffer.
As Rahm tried to catch the 28-year-old, his dreams of his own third major triumph were crushed on the tricky ‘Green Mile’ finale.
He made a bogey on 16 before sending his tee shot into the water on the par-three 17th on his way to a double-bogey five. Two more dropped shots on the last hole saw him topple to a tie of eighth.
Above him, Bryson DeChambeau continued his fine recent record in majors by finishing in a share of second alongside fellow Americans Davis Riley and Harris English, whose six-under round of 65 catapulted him up the leaderboard.
Rory McIlroy, playing his first major since completing a career Grand Slam at the Masters in April, finished with a 72 to end three over par in a tie for 47th.
Defending champion Xander Schauffele fared marginally better, shooting 68 on Sunday to finish one under for the event and sneak inside the top 30.
More to follow.
