The Colonials (18-8, 9-4 Northeast Conference), who will host the Red Flash on Saturday, trailed 35-24 at the 2:19 mark. St. Francis shot 68.4 percent (13 of 19) from the field in the first half.
Tied at 41, Robert Morris used a 15-4 run to build its own 11-point cushion. The Colonials, who shot 63 percent after the break (17 of 27) still led 70-61 with 4:10 left when St. Francis (5-19, 4-9) made a 9-2 run to get to 72-70 with 1:25 remaining.
Russell Johnson's layup made it 74-70, then Anthony Ervin, who led St. Francis with 20 points, hit two free throws. Velton Jones and Coron Williams made two free throws each in the final 15 seconds to preserve the win.