Masterful on the greens, Day rolled in birdie putts of 28 feet or more at the 10th, 14th and 15th in a dominant performance in the first of four tournaments in the season-ending playoffs — in which a $10 million bonus will go to the series winner after the Tour Championship in September.

Sweden's Henrik Stenson was a distant second after a 66 for 267. Stenson tried to keep things interesting, shaking off an early bogey with three straight birdies starting at the fifth, then trimming Day's four-shot lead to two after birdies at the 10th, 13th and 14th.

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But Day plumped his cushion back to three strokes with a 28-foot birdie bomb at 14, and after Stenson bogeyed the par-five 16th to fall four back it was clear sailing for Day.

He didn't take his foot off the gas, rolling in a 33-foot birdie putt at 15 and draining a 10-foot birdie at the last.