Tony Johnson's jumper with just four seconds left lifted Lafayette to a 63-62 upset win over first place Bucknell at the Kirby Sports Center on Saturday.
Lafayette trailed much of the game before rallying in the second half.
The Leopards improve to 6-4 in the Patriot League with the win, while Bucknell drops to 8-2.
Johnson had 17 points, five assists and four rebounds.
Seth Hinrichs had a team-high 20 points while Joey Ptasinski added 14.
Mike Muscala had a game-high 29 points and 15 rebounds for the Bison.
Bucknell will travel to Lehigh Monday night with sole possession of first place in the Patriot League on the line.