There was a four-way tie at the top of the leaderboard at the midway point as Knox, Danny Willett, Ross Fisher and Kevin Kisner were locked together on 17 under.

But the 30-year-old pulled clear to finish on 20 under, beating Kisner by two strokes.

He told Sky Sports 4: “It’s unbelievable. I always kind of thought I would win a big one as my first and it’s going to take a long time to sink in.”

Jordan Spieth tied for seventh place, while Rory McIlroy finished in a share of 11th on 14 under.

When the fourth round began, it was clear that low scores would be possible as Willett flew out of the blocks with four birdies in a row to get to 11 under.

Knox opened his final round with a par at the first before firing back-to-back birdies at the second and third to move to 18 under.

The Scot bounced back from a bogey at the fourth with a gain at the sixth, before dropping another shot on the par-four ninth to reach the turn in 35.

But Knox began his back nine with a brace of birdies before adding another at the 16th to finish the day on 68.