Freshman Jaylen Brown scored 27 points but Cal struggled defensively in a 94-90 loss to Richmond in the third-place game of the Las Vegas Invitational.
The No. 14 Bears (4-2) are almost certain to drop out of the Top-25 after losing on consecutive nights at the Orleans Arena.
Brown, coming off a seven-point effort against San Diego State in which he fouled out, hit 11 of 16 shots to score a career high.
But Terry Allen scored 34 points for the Spiders (4-2), including 11 of 12 from the free throw line. Richmond shot 31 for 39 at the line, as Cal committed 25 fouls.
Richmond scored 50 second-half points.
Cal was efficient enough on offense, converting nearly 54 percent of its shots and turning the ball over just eight times a night after it shot 37 percent with 15 giveaways.
Tyrone Wallace had 15 points, Ivan Rabb contributed 13 points and seven rebounds and Jabari Bird scored a season-high 12. Sam Singer scored 12 points off the bench, which provided the Bears 18 points.
Sharpshooting guard Jordan Mathews was just 1 for 8 from the floor and scored a season-low three points.