Gary Nicklaus and former amateur star Luke Donald also made big moves Friday at the Bear Creek Country Club.
The low 35 players and ties from the 167-man field will earn playing privliges on the 2002 tour.
Perez put himself in excellent position to grab one of those spots by reaching 18-under 198 for 54 holes. He had a two-shot lead over tour veteran Tommy Armour III, who got to 200 by firing a 67.
Tied for third at 202 were Ben Crane, Kevin Durkin and second-round leader Hidemichi Tanaka, who shot a 70 Friday.
Nicklaus, who failed to earn enough money in 2001 to keep his tour card and was forced to re-enter the grueling qualifying event, moved into a tie for seventh at 204 by firing a 65. Nicklaus began the day tied for 33rd.
Former tour winners Blaine McCallister and Robert Gamez were among the large group tied for 12th at 205.
Donald, from England, turned pro this year after the Walker Cup matches and he opened the tournament with two rounds of 71. But he shot a 65 Friday that vaulted him from a tie for 73rd to a tie for 26th at 207.
Ty Tryon, trying to earn his tour card at age 17, recorded a 71 that caused him to slip back from a tie for 33rd to a tie for 61st