Scotland's Russell Knox claimed the biggest victory of his blossoming career as he tasted victory on his World Golf Championship debut by winning the HSBC Champions in Shanghai by two shots.

Knox, who was a late replacement for JB Holmes, was first out on the course on Sunday morning as he completed the 18th hole of his third round with a birdie to move to 16 under.

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 Inverness exile pulled clear to finish on 20 under, beating Kisner by two strokes, as he landed his first PGA Tour triumph.

"It's unbelievable," said the Florida-based Knox. "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 with a 68