Rory McIlroy endured a miserable start to the US PGA Championship as Jimmy Walker claimed the early lead in round one at Baltusrol.
Playing in the star grouping of Thursday morning alongside Phil Mickelson (71) and world number one Jason Day, who began his title defence with a two-under 68 despite seeing his preparation hampered by illness and his wife being hospitalised with an allergic reaction, McIlroy slumped to a 74.
That left the US PGA champion of 2012 and 2014 at four-over and nine strokes behind Walker, who stormed out of the blocks with five birdies in his first 10 holes after starting on the back nine.
Argentina's Emiliano Grillo (66) was Walker's nearest rival midway through the opening day, with two other relatively unheralded players, Harris English and James Hahn, among those a shot further back.
Rickie Fowler, Brooks Koepka and KJ Choi were others to make strong starts with two-under rounds of 68 on a sweltering hot day in New Jersey.
Mickelson - the winner the last time this tournament was held at Baltusrol 11 years ago - had been tipped by many to challenge this week following his impressive performance in The Open at Royal Troon, where he finished second to an inspired Henrik Stenson but 11 shots clear of JB Holmes in third.
Like McIlroy, the veteran American also struggled badly over his opening nine, but recovered much of the damage with three birdies in his final seven holes.
Day was comfortably the pick of his group, off-setting a solitary dropped shot with three birdies in an encouraging start to the tournament.
Jordan Spieth was among the afternoon starters, along with the winners of the year's first three majors - Danny Willett, Dustin Johnson and Stenson - who are playing together for rounds one and two as is traditional at this event.