Sisk and Schmidt both shot rounds of 5-under 67 to take a one-shot lead over Shea Lague and Skyler Ngo, who shot rounds of 4-under 68 and are T3.
Sisk, a former golfer at San Jose State and recent graduate at USC recorded seven birdies and two bogeys in the round.
He got off to a blazing hot start, going 5-under through his first eight holes. He played the other 10 holes at even par with two birdies and two bogeys.
Schmidt had a cleaner scorecard, going bogey-free and making five birdies. He birdied Holes No. 2, 4, 12, 15, and 18.
Jason Bittick shot an even-par 72 in the Senior Division to take a one-shot lead into the final round.
Brian Smyth shot 1-over 73 to sit in solo second place, and Tony Ralph and Jim Plotkin shot rounds of 2-over 74 to sit T3.
