Trapped among the trees 155 yards from the hole and not able to see the green, the left-hander hit a huge hook Sunday and landed the ball safely on the 10th green.
He two-putted for par and because Oosthuizen couldn’t get up and down from the front of the green, Watson had captured his first major.
Watson birdied Nos. 13 through 16 to rally from as many as four shots off the lead. Oosthuizen grabbed that lead on No. 2 when he holed out from the fairway for a rare double-eagle 2.
But it was Watson who hit the shot of the day — the approach on No. 10 that helped him win the first Masters playoff since 2009.