The Golden Flashes (8-3) trailed by as many as 11 in the first half and 24-21 at halftime. After the Bulls (5-5) took a 31-25 lead with 15:59 left to play, Kent State scored eight straight to take its first lead on Guyton's layup with 12:31 to go.
The Bulls would regain the lead, 35-34, a little over four minutes later but Guyton again put the Golden Flashes on top. His 3 with 7:39 left gave Kent State a 37-35 advantage, and it wouldn't trail the rest of the way.
Porrini finished with 16 points, Guyton 13 and Justin Greene added 15 points and 14 rebounds for the Golden Flashes.
Jawanza Poland led the Bulls with 15 points.
Kent State honored its 2002 NCAA Elite Eight team, which was coached by USF Coach Stan Heath.