Briny Baird fired the lowest round of his career, an eight-under-par 63, to surge three shots clear of the field after the first round of the Buick Classic.
Jim Furyk, winner of last week's US Open, and Joey Sindelar shared second place on 66, with world number one Tiger Woods, South African Retief Goosen and Shigeki Maruyama of Japan a further stroke adrift at the Westchester Country Club.
South African duo Deane Pappas and Ernie Els, JL Lewis and Skip Kendall were tied on three-under 68.
Baird, whose previous best round was a 64, has already earned $982,105 this year with four top-10 finishes.
Furyk, meanwhile, is experiencing no letdown after winning his first major at Olympia Fields last Sunday and has been one of the tour's most consistent players all season, with 11 top-10 finishes in 14 starts.