The points were a career high for Diop, who also had a career-best eight rebounds.
Gerel Simmons led Brevard (1-6) with 18 points on 5-of-9 shooting from the field and a 7 of 8 performance from the foul line. Simmons was fresh off a 22-point performance against Mars Hill that included a buzzer-beating game-winner.
Brevard jumped to a 13-4 lead as Winthrop shot 2 of 12 to start the game. The Eagles then went on a 12-4 run, capped by a three-point play by Gamble.
Winthrop led 35-31 at halftime then shot 61.5 percent (16 of 26) in the second half to earn the 23-point win.
Mike Krzyzewski says he has good reason to be excited for next season thanks to a combination of Duke's incoming freshmen and a core of experienced upperclassmen.
Georgia guard Juwan Parker has been awarded a medical redshirt, leaving him with two years of eligibility, after missing the 2015-16 season with a partially torn Achilles tendon.
Forward Trevon Bluiett has withdrawn from consideration from the NBA draft and will return to Xavier for his junior season.