Curtis, the tallest player on the court at 6-foot-8, hit two key jumpers in the final 5:07 to end two short Winthrop rallies and Trevor Gaskins helped the Rebels (8-0) remain undefeated and off to their best start since the 2000-01 season with a game-clinching 3-pointer late.
The Eagles (5-4), who were led by Antwon Harris' 17 points, led by as much six in the first half and built a 46-39 lead after a 13-4 run to start the second half. But Huertas ended that run when he hit 3-pointers from the same spot on the right wing just 23 seconds apart to cut Winthrop's lead to 46-45 with 15:74 remaining.
That started a 20-8 run that included five points from Chris Warren, who finished with 10 points and five assists.
The Eagles, three-time Big South champions looking for another win over a major conference team after upsetting Georgia Tech earlier this season, remained in the game till the final 2 minutes.
Chris Gaynor hit a 3-pointer to pull the Eagles within 69-67 with 3:33 to go, but Gaskins hit a 3-pointer from the right wing with 2:12 left to seal the win.
Gaskins scored 10 for the Rebels, who are three wins away from matching their 11-0 start in 2000-01.