The Lions (6-6) trailed 17-11 with 5:01 left in the first half before scoring 13 straight points to lead 24-17 at halftime. Ago scored 11 points during the spurt and capped the run on a 3-pointer with 1:24 left in the first half.
American reclaimed the lead, 35-34, on Riley Gaft's 3 with 10:53 to go, but the Lions outscored the Eagles 17-10 over the next 8:26. Ampim put Columbia ahead 51-45 on a layup with 2:27 remaining to snap its two game losing streak.
The Lions, the nation's top 3-point shooting team at 46.6 percent, hit 83.3 percent of their long-range shots (5 of 6) against American.
Vlad Moldoveanu scored 18 points for the Eagles, who lost for first time in four meetings against Columbia.