Travis Weatherington scored 15 points with four 3-pointers and John Carroll added 13 points and grabbed 14 rebounds for the Hawks (8-8, 1-0 America East Conference), who eked out their second straight overtime win.
Trailing by two, the Retrievers (9-8, 1-1) missed their last four shots in the final two minutes of overtime, including a 3-pointer at the buzzer as Ricky Council's try with one second left was just off the mark.
K.J. Jackson's 30-footer at the end of regulation for UMBC bounced off the front of the rim, leaving the score tied at 59.
Hartford's Weatherford was fouled behind the arc and made all three free throws, cutting the gap to 59-57 with 1:37 to go. UMBC missed three straight from the floor before Lynch sank a pair from the line to force overtime.
Joe Sherburne scored 17 to lead UMBC before fouling out with five seconds left in OT.
Coach K, Duke land blue-chip '20 guard Steward
D.J. Steward, a five-star shooting guard in the 2020 class, selected Duke over Texas and Louisville, giving Mike Krzyzewski his third five-star recruit in next year's class.
Spinal surgery gives UConn's Hurley new outlook
Less than two weeks after having surgery for a degenerative spinal condition that required replacing two disks in his neck with artificial ones, UConn coach Dan Hurley is back at work full time.
The complicated legacy of Rick Pitino
Rick Pitino's resume as a basketball coach is largely one of success, but his off-court controversies have left a shadow over his legacy.