However, its a guy two off the pace whos the big surprise.
Seventy-year-old Gene Littler recorded six birdies and one bogey for a 5-under-par 67.
Littler first joined the Senior PGA Tour in 1981. Hes an eight-time tour winner, with his most recent victory coming in 1989. Littler also won 29 times on the PGA Tour, including the 1961 U.S. Open.
Littler was bogey-free through his first 17 holes, before a slight slip at the home hole.
Walter Hall, Allen Doyle, Hubert Green, Tom Kite, Gil Morgan, Stewart Ginn and Sammy Rachels also shot 67 to tie Littler for fourth place.
Jim Ahern is in third place alone after a round of 6-under-par 66.
After bogeying his first hole, Canizares played his back nine in 5-under-par 31 to post his round of 65; Irwin shot his by birdieing his first three holes and sinking a 45-foot eagle putt on the par-5 finishing hole.
Canizares and Irwin are each in search of their second victories of the season. The 54-year-old Spaniard defeated Morgan on the ninth playoff hole in the Toshiba Senior Classic, while Irwin won the Siebel Classic in Silicon Valley.
Irwins triumph was the 30th in his career ' a Senior PGA Tour record. Canizares triumph was his first.
Orville Moody wasn't able to shoot his age on Friday, but he came awfully close. The 67-year-old fired a 4-under-par 68 in the first round.
Full-field scores from Bruno's Memorial