The Saints came in with the longest winning streak in the nation, but were stung by a tenacious Purple Eagles defense that forced 16 turnovers and had nine steals.
Kashief Edwards added a career-high 20 points, and Bilal Benn finished with 15 for Niagara (14-13, 7-8 Metro Atlantic Athletic Conference), which lost to Siena in the MAAC championship game last March.
Down by one point with 15 minutes left in the second half, the Purple Eagles pulled away with a 21-3 run that was capped by Demetrius Williamson's 3 with 9:54 to go that made it 70-53.
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