The 'guesswork' behind Spieth's stunning Open victory revealed

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No little luck, a truckload of talent and a sprinkling of guesswork. That's how Jordan Spieth won The Open at Royal Birkdale.

The last factor we know thanks to a note left by his caddie Michael Greller, referencing Spieth's near horror-show at the 13th on Sunday.

Having seen an overnight three-shot lead ahead of Matt Kuchar wilt, Spieth drove almost 100 yards right of the fairway at 13, his ball landing in an unplayable patch of rough halfway up a hill.

Having taken to the practice range for a penalty drop, Spieth recovered a bogey before a stunning birdie-eagle-birdie-birdie run put him back in command.

That approach to the 13th hole, played from behind a few temporary stands and broadcast trucks was a difficult one to measure given its bizarre location and Greller's post-round notes revealed: "No number [yardage]. We guessed 240 yards."

Having played a shot that your average club golfer might sympathise with, what followed was truly out of this world, helping Spieth secure the third leg of a career Grand Slam, with his final hurdle - the US PGA Championship, to follow next month at Quail Hollow.