Art Parakhouski had his nation-leading 24th double-double and scored the winning basket as Radford rallied from a 14-point deficit to defeat Winthrop 54-52 on Saturday.
The game determined the No. 2 seed in the Big South Conference tournament.
Parakhouski was 8-for-18 from the field to score 24 points with 15 rebounds for the Highlanders (18-11, 13-5), who have won four straight and seven of eight. Radford also swept the series.
Winthrop (16-13, 12-6) had its biggest lead at 32-18 and led 52-40 with 9:25 to go.
The Highlanders used a 12-0 run, capped by a Parakhouski layup to tie the game at 52, but Parakhouski missed the subsequent free throw. Amir Johnson stole the ball from Mantoris Robinson with 22 seconds left, setting up a Parakhouski layup with 1 second to go.
Joey Lynch-Flohr added 12 points for Radford.
Robinson paced Winthrop with 14 points.