Stanford (21-11) built an early 10-point lead, answered when Arizona State tried to make a run and pulled away down the stretch to give its NCAA tournament hopes a huge boost.
Dwight Powell scored 15, Josh Huestis added 12 and the Cardinal shot 54% to earn a spot in Friday's semifinals against second-seeded UCLA.
Arizona State (21-11) got off to a sluggish start for the third straight game and never fully recovered as its top players struggled against Stanford's defense.
Colorado (23-10) led by as much as 11 before the Bears made a late run to make it close.
The Buffaloes went ahead 58-54 when Booker made two free throws with 12.1 seconds left, but Eli Stalzer only converted one of two free throws after Justin Cobbs scored on a layup.
Cal raced down the court to get off a potential tying three-pointer, but Cobbs' shot came up short.
Josh Scott scored 11 points for the Buffaloes, who will face top-seeded and No. 4-ranked Arizona in the semifinals Friday night.
Cobbs finished with 21 points, five assists and four rebounds. Tyrone Wallace added 13 points for Cal (19-13), which shot five of 22 from three-point range.
Arizona 71, Utah 39: Nick Johnson scored 14 points, T.J. McConnell added 13 and No. 4-ranked Wildcats overwhelmed the Utes defensively in a rout to match the most lopsided game in Pac-12 tournament history.
After playing two close games against Utah during the regular season, top-seeded Arizona (29-3) opened the tournament with a spirit-crushing defensive performance.
Energized by a raucous crowd that made it feel like the McKale Center, the Wildcats provided a glimpse of what can happen when one of the nation's best defenses gets rolling.
Arizona ran through the record book against Utah (21-11), setting marks for fewest points allowed, fewest field goals (12) and lowest shooting percentage (25).
Jordan Loveridge and Delon Wright, Utah's leading scorers, combined for seven points on one-of-four shooting.