"We have to become a little bit more unselfish on the offensive end," Justus said.
The zero assists in the second half, Justus said, showed "the ball was sticking a little bit."
With 21 turnovers, Kentucky's assist-to-turnover ratio was one-to-4.1.
Richmond (2-0) pulled away in the second half. A 21-10 run left Kentucky behind 72-56 with less than two minutes left.
Blake Francis and Nathan Cayo led Richmond with 18 points apiece. Two teammates chipped in double-digit points.
After a slow start, star guard Jacob Gilyard led Richmond to a 48-32 handling of Kentucky after the break. He had all but one of his six assists after halftime and finished with five steals.
Gilyard, who led Division I in steals last season, is on the preseason watch list for the Bob Cousy Point Guard of the Year award.
"You are obviously aware of the kind of impact he has had on many games during his time at Richmond ...," Justus said. "You have to be prepared for that. ... And we were. ...
"Our guys are smart enough to know the premium you've got to have on backcourt play to be successful here (and) to be successful anywhere."
In the first half, Richmond made only 10 of 35 shots (two of 12 from three-point range). The Spiders' combination of experience and Princeton style of offense made no impression.