Lutete was 9 of 13 from the field including four from distance for the River Hawks (2-3). Obadiah Noel added 19 points and five rebounds, Alex Rivera had 16 points and Josh Gantz scored 15 points with seven rebounds and four assists.
UMass trailed 31-25 late in the first half but rallied in the final six minutes with the help of a pair of 3-pointers by Lutete and another by Gantz to take a 44-42 edge at the break.
The River Hawks opened the second period on a 13-5 run to make it 57-47 with 16:09 to play. But Army continued to threaten, closing to 80-79 with 2:55 left before Rivera hit two jumpers and Noel made all six of his free throws in the stretch to help keep the River Hawks on top.
Matt Wilson scored 23 points with eight rebounds to lead the Knights (1-3).