KIAWAH ISLAND, S.C. (AP) – Phil Mickelson has become the oldest major champion by surviving a somewhat chaotic final round at the PGA Championship. The 50-year-old Mickelson squandered most of a five-stroke lead on the back nine before finishing two strokes ahead of Brooks Koepka and Louis Oosthuizen at Kiawah Island. Mickelson closed with a 1-over 73 to finish 6 under for his sixth career major championship. Julius Boros was 48 when he won the 1968 PGA Championship in San Antonio. Boros held the distinction of oldest major champ for 53 years before Mickelson added to his legacy. Lefty also became the first player to win tournaments 30 years apart, and the 10th to win in three different decades. Koepka was 4 over on the par 5s when the game was still on and closed with a 74. Oosthuizen hit into the water as he was trying to make a final run and shot 73.