The Russian defeated the German in four tough sets on his way to the final here in 2019 but was never threatened in this match, hitting 23 winners, firing eight aces, and breaking seven times in the one hour, 48 minute contest.
Koepfer served poorly, winning just 57 percent of his first serve points and 42 percent of his second serve points while only hitting 17 winners and committing 29 unforced errors.
2019 finalist roars through German, into third round
Medvedev broke in a marathon opening game, lasting 16 points with the world number two assuming the lead on his fourth break chance after Koepfer dumped a forehand into the net.
The Russian lost his serve midway through the set as Kopefer leveled the score at 3-3, but rebounded straightaway, driving a backhand into the corner and reclaiming the lead at 4-3.
Serving for the set at 5-4, Medvedev reached triple set point after a backhand error by the German and he whipped a forehand winner down the line to clinch the set.
The Russian was on top immediately in the second, breaking Koepfer after the world number 57 was wide with a forehand. He broke for a second time in the set to go in front 4-1 and a forehand into the net by the German on set point put Medvedev in full control.
Another forehand error by Koepfer gave the Russian a quick 2-0 lead in the third set and it was smooth sailing to the finish line as on his third match point, Medvedev struck a forehand that the German offered no reply to.