Germany's Martin Kaymer hugs his wife after his playoff win. (Reuters)

KOHLER, Wisconsin (Reuters) — Germany's Martin Kaymer maintained ice-cool composure to win his maiden major title in a gripping two-way playoff with American Bubba Watson for the 92nd US PGA Championships on Sunday.

With American Dustin Johnson having earlier been eliminated from the playoff in stunning fashion after being handed a two-stroke penalty, Kaymer went on to clinch the prized Wanamaker Trophy over three extra holes at Whistling Straits.

“I cannot win anything bigger,” the beaming 25-year-old told reporters after becoming only the second German to land a major title. HIs compatriot Bernhard Langer clinched the US Masters in 1985 and 1993.

“The majors, they are the biggest tournaments we play. It's cool to see my name (on the trophy) next to Jack Nicklaus, Arnold Palmer and all those guys. It will take me a while to realise what has happened.”

Kaymer's victory made him the sixth first-time winner in the last seven majors with Phil Mickelson's emotional victory at the US Masters in April the sole exception.

Watson holed a three-foot birdie putt at the first playoff hole, the par-four 10th, but Kaymer immediately responded by sinking a 15-footer to birdie the treacherous 223-yard 17th.

The German then sealed victory in the year's final major with a bogey at the par-four 18th after both players found the right rough off the tee.

The long-hitting Watson struck his second shot into a creek guarding the front of the green on the way to a double-bogey six. Kaymer laid up with his second shot and struck his third to 15 feet before two-putting for the title.