Djokovic claimed a men's record 23rd Grand Slam title at the French Open last month to leapfrog Rafa Nadal and go three ahead of another great rival in Roger Federer, with the 36-year-old eyeing an eighth crown at Wimbledon which begins on Monday.
Victory in London will leave Djokovic level with Margaret Court on 24 major titles atop the all-time list.
"I don't know how does he do it," Medvedev told reporters. "I think if I saw it right, Novak is almost 50%. I think I saw he played 70 majors and 35 (34) he was in the final. I don't know how it is possible. He doesn't have bad days?
"Actually, he does, like everybody. Even on these bad days, he manages to beat the opponent. It's actually tough because it's one against one. Both of them want to win.
"I don't know how he's doing it. That's why he's for me the greatest in the history of tennis. But this is basically, of course, debatable."
Having also won the Australian Open at the start of the year, Djokovic is looking to keep alive his hopes of a calendar year Grand Slam - winning all four majors in a single year.
Medvedev famously beat Djokovic in the 2021 U.S. Open final to deny the world number two the feat at the final hurdle.
"To be able to beat him when he was going for a Grand Slam, maybe he was a little bit tighter than usual, but I played an amazing match," Medvedev said.
"This gives me even more pride that I was able to do it, given what he continued to do after this.
"I'm just happy I was able to do it. I don't want to stop. I want to try to continue to play against him again in finals, or against anyone else. That's what I didn't manage to do since some time."
