Neil Watson scored 18 points, including a 3-pointer with 18.5 seconds left, as Southern Mississippi held off Marshall 67-63 Saturday night.
The Golden Eagles (17-3, 4-1 Conference USA), who led by as many as 16 points in the first half, saw the Thundering Herd hit three consecutive 3-pointers to pull within 64-63 with 46.5 seconds to play.
But Watson, who scored Southern Miss' final five points of the game, swished a shot off the right wing with the shot clock winding down to give the Golden Eagles all the cushion they would need.
Southern Miss handed the Thundering Herd its first league loss.
LaShay Page added 15 points for Southern Miss.
Page scored all his points in the first half as the Golden Eagles ran out to a 42-30 edge at halftime.
Marshall's DeAndre Kane led the Thundering Herd (13-6, 4-1) with 21 points.