The Rams (18-6, 10-3) are a half-game ahead of Dayton and VCU, both at 9-3. UMass (16-10, 9-4) fell out of what was a four-way for first place.
Jered Terrell added 14 points and Jarvis Garrett 13 for Rhode Island, which beat the Minutemen for the first time in eight meetings. UMass beat the Rams at home 60-56 on Jan. 17. Martin's double-double was his seven this season and 11th of his career. He also had four blocks.
Rhode Island went on a 9-0 run to lead 45-30 with 13:26 remaining. The Minutemen never got closer than nine after that.