Coach David Shaw said after practice Thursday night that Cajuste is still recovering from a bruised right knee suffered in last weekend's win over UCLA. Williamson will miss his second straight game with a leg injury.
Shaw is hopeful both can return for Stanford's home game against No. 2 Oregon on Nov. 7.
Cajuste ranks second on the team with 21 receptions for 377 yards and four touchdowns this season. Jordan Pratt, the 28-year-old former minor league baseball player, will make his first career start in Cajuste's place. Kodi Whitfield and Michael Rector also will play more as reserves.
Redshirt freshman Conrad Ukropina will start for Williamson again. Ukropina missed a 46-yard field goal and connected from 31 yards in Stanford's 24-10 victory against UCLA.