SPRINGFIELD TOWNSHIP, N.J. -- Jimmy Walker shot an opening-round, 5-under-par 65 to claim the early lead after his Thursday morning round at the 98th PGA Championship on the Lower Course at Baltusrol Golf Club.
Walker, a five-time winner on the PGA Tour who is ranked No. 48 in the world, sank six birdies opposite a bogey on No. 6 to claim a one-shot lead over Emiliano Grillo of Argentina.
The 37-year-old Oklahoma City, Okla. native has never won a major tournament, finishing as high as tied for seventh at the 2014 PGA Championship.
Walker's best finish on tour this season was a tie for fourth at January's Farmers Insurance Open. He currently ranks 50th in the 2016 FedExCup standings (752 points) and 57th on the money list ($1,471,771).
Grillo also rolled in six birdies, but made two bogeys. Harris England and James Hahn were tied for third after carding 67s. Seventh-ranked Rickie Fowler came in with a 68 to headline a large tie for fifth.
Defending PGA Championship winner Jason Day of Australia was 2 under, tied for 7th place.
The top-ranked Day earned a three-shot victory over Jordan Spieth to secure his first major championship at last August's PGA Championship at Whistling Straits in Mosel, Wis. Spieth was shooting par after 8 holes in his first round Thursday.
Phil Mickleson, who won the PGA Championship at Baltusrol in 2005, bogeyed four of his first 11 holes, but bounced back with birdies on Nos. 3, 6 and 7 to climb to 1-over through 17 holes.
Fourth-ranked Rory McIlroy of Northern Ireland was 4 over after four bogeys through 17 holes.
A trio of 2016 major winners -- ninth-ranked Danny Willett of England (Masters), second-ranked Dustin Johnson (U.S. Open) and fifth-ranked Henrik Stenson of Sweden (British) -- tee off at 1:45 p.m. ET.