Matsuyama wins first US title in Memorial playoff
Hideki Matsuyama of Japan holds the trophy after winning the Memorial Tournament presented by Nationwide Insurance at Muirfield Village Golf Club on June 1, 2014 in Dublin, Ohio - by Andy Lyons
Matsuyama endured a rocky back nine at Muirfield Village that included a double-bogey five at the par-three 16th.
But he birdied the 72nd hole of regulation to complete a three-under 69 and join Na on 13-under 275.
South Korea-born American Na had been in the clubhouse for some two hours having completed a bogey-free eight-under par 64 for 275.
Matsuyama's hopes looked dim when he hit a poor tee shot at the final hole of regulation. He broke his driver bouncing it on the ground in disappointment.
However, he knocked his approach shot to five feet for a birdie.
They returned to 18 for the playoff, and Na was in a stream off the tee.
Matsuyama was in a bunker off the tee but he drained a 10-foot putt for par to seal the victory.
The 22-year-old Asian star, who won four times on the Japan Tour last year, is in his first season on the US PGA Tour. He became the fourth Japanese player to win on the US tour.
Masters champion Bubba Watson went into the final round of the tournament hosted by Jack Nicklaus with a one-shot lead.
However, he fell back with a bogey at the14th and a double-bogey seven at the par-five 15th and missed out on the playoff by one stroke.
Watson finished alone in third after an even par 72 for 276.