Phil Mickelson became the oldest major winner in golf history on Sunday, the 50-year-old left-hander capturing the PGA Championship by two strokes for his sixth and most iconic major title.

The age-defying American took the $2.1 million (1.7 million euro) top prize with an epic victory for the ages, producing a dazzling shotmaking display at windy Kiawah Island's while younger rivals faded.

"It has been an incredible day," Mickelson said. "Certainly one of the moments I'll cherish my entire life."

Mickelson erased the major age win mark set by American Julius Boros when he captured the 1968 PGA Championship at age 48.

"I don't know how to describe the feeling of excitement and fulfillment and accomplishment to do something of this magnitude when very few people thought that I could," Mickelson said.

Mickelson grinded out a final-round one-over par 73 to finish 72 holes on six-under 282 with South Africa's Louis Oosthuizen, the 2010 British Open champion, and American Brooks Koepka, a four-time major winner, sharing second on 284.

It was the first major victory for Mickelson since the 2013 British Open.

"This is just an incredible feeling because I believed that it was possible but yet everything was saying it wasn't," Mickelson said. "I hope others find that inspirational."

Tiger Woods, a 15-time major winner and long-time Mickelson rival, did, tweeting: "Truly inspirational to see @PhilMickelson do it again at 50 years of age. Congrats!!!!!!!"

It was the 45th career US PGA Tour triumph, his first since 2019 at Pebble Beach.

Mickelson improved to 4-for-6 in majors with 54-hole leads or shared leads, winning at the 2004 and 2006 Masters and the 2005 and 2021 PGA but sharing second at the 2006 and 2013 US Opens.

His other major wins came at the 2010 Masters and the 2013 British Open.

With 16 years between PGA Championship triumphs, Mickelson owns the longest gap between wins at the same major.