Irwin shot 7-under-par 65 to finish a full five strokes ahead of Tom Watson, who opened in 77, and eventual Player of the Year, Allen Doyle.
Obviously, Im delighted to say the least, said Irwin after his victory. The day went, probably, better than I had hoped.
Irwin started the final round leading by one, but pulled away from the field with an eagle on the par-5 fourth hole and five birdies. He finished the tournament at 10-under 206.
Quick greens at the Coyote Creek Golf Club in San Jose, Calif., combined with swirling winds to frustrate players for two rounds. The third round was more tame, though it was delayed for two hours due to heavy fog.
Irwin went on to record two more victories in 2001 to up his total to 32. He added to that with No. 33 at this years ACE Group Classic in February, and No. 34 at last week's Toshiba Senior Classic. The three-time U.S. Open champion is five victories clear of second place on the all-time list, Lee Trevino.
Seventy-eight players will vie for the $210,000 first-place prize. The field includes Doyle, Bruce Fleisher, Gary McCord, Larry Nelson, Andy North, Doug Tewell and Fuzzy Zoeller.
This is the third consecutive event staged in the Golden State. The tour will head south to Florida for the next two tournaments.
Full field and tee times for the Siebel Classic in Silicon Valley