The world No. 1 bolted out to a 6-1 lead, converting both of his break point chances and winning 56 percent of return points.
The match took an unexpected turn after the players changed ends with Djokovic set to serve at 6-1, 3-2. The Serbian was broken, but who knew what was to come from Zverev.
The German closed out the second set full of confidence, and grabbed his first lead of the match when he fended off four break points to hold for 2-0 at the start of his decider with the 2008 bronze medalist.
As for Zverev, standing between him and a gold medal is Karen Khachanov. Zverev won their first two clashes, before the Russian hit back to take the next two. The winner will join Rafael Nadal and Andy Murray as active Olympic men's singles champs.