With just 12 seconds remaining in the game, Coby Karl lofted up a runner in the key. The shot banked off the glass and hit the front rim, and Acy powered through for the one-handed follow dunk, finishing up and over Cohen, who went crashing to the court. The basket cut Phoenix's lead to 99-96.
Phoenix went on to advance to the summer league semifinals on Sunday with a 103-98 win.
Acy finished with 28 points and 10 rebounds in 34 minutes for the Raptors. Marcus Morris led the Suns with 23 points, six rebounds and three assists.
RELATED: Kent Bazemore throws down poster dunker in Las Vegas | Jeffery Taylor throws down poster dunk in Las Vegas | Mason Plumlee throws down poster dunk in Orlando | Reggie Jackson throws down poster dunk in Orlando
Acy, 22, averaged 4 points and 2.7 rebounds in 29 appearances for the Raptors last season. A 2012 second-round pick, Acy spent four seasons at Baylor.
Cohen, 22, spent four seasons at Davidson before going undrafted in 2013.