A three-point play by Fouse sparked a 12-4 run, during which Sykes scored six, that gave the Phoenix a 20-11 lead midway through the first half.
Sykes hit a 3-pointer to give Green Bay a 23-point lead with 1:43 left, but Minnesota-Duluth scored the final seven to make it 45-29 at the break.
The Bulldogs would get no closer.
Brett Ervin led Minnesota-Duluth with 13 points and Reece Zoelle added 10.
Green Bay made 30 of 58 (51.7 percent) field goals, including 6 of 11 (54.5 percent) from 3-point range, and forced 16 turnovers.
Minnesota-Duluth was just 4 of 18 from behind the arc and 4 of 10 from the free throw line.