Stephen Lumpkins scored 21 points and American jumped ahead early in a 73-60 victory over Lafayette on Saturday.
Vlad Moldoveanu added 17 points and Troy Brewer scored 13 points for the Eagles (15-7, 5-2 Patriot League), who guaranteed themselves sole possession of second place at the midway point in conference play.
Jared Mintz scored 12 points for the Leopards (8-14, 3-4), who fell to their third straight loss, sank to 1-10 on the road and suffered their 13th straight defeat against American.
Ryan Willen scored 11 points and Jim Mower added 10, including a 3-pointer, to close what was a 19-point deficit to 69-60 with 1 minute to play.
But American hit its last four free throws and nine of its last 10 to seal the victory, while shooting a season-high 53.3 percent (8 of 15) from 3-point range.
Early, Moldoveanu hit three 3-pointers and Brewer hit two during the opening six minutes as American leaped out to a 17-6 lead.
Lumpkins converted a leaning jumper and resulting three-point play to make it 24-11, and Moldoveanu's layup off Daniel Munoz's feed capped a 6-0 spurt and made it 37-21 late in the half.
Steve Luftak's 3-pointer made it 40-23 to start the second half, and Simon McCormack hit a runner to cap another 6-0 stretch, making it 51-32.
Lafayette responded with a 10-2 run that made it 53-42 after Rob Delaney's free throw. But the Leopards failed to get closer until Tony Johnson hit a pair of free throws that made it 66-56 with 1:37 left, and Mower's 3 from the left gave Lafayette a sliver of hope late.
American outrebounded Lafayette 35-26 and won the battle of points in the paint, 28-14.