For the second consecutive match the Russian squandered a late third-set lead, falling 6-3 6-7(5) 7-6(2) to the Serb to finish winless in his three group-stage matches at the prestigious year-end championships in Turin.
"Super easy: I sucked," Medvedev said bluntly when asked why he was unable to serve out the match, which was a dead rubber with the undefeated Djokovic already through to the semifinals and Medvedev eliminated.
"That's what happened. It's disaster. What I'm really happy is that this match didn't count in going out of the group, otherwise I would have two matches where I lost serving for the match.
"But, yeah, that's awful. I'm going to try to be better next time. I have no other choice."
The Moscow native won his lone major title by beating Djokovic in the 2021 US Open final and rose to world number one in February.
But he will finish the year outside the top five after winning just two titles this season, the bigger being the ATP 500 Vienna Open last month.
Despite the dismal finish, Medvedev said his performance in Vienna and earlier in October in Astana - where he made the semifinals but was forced to retire from the match against Djokovic with a leg injury - gave him hope.
"If I wouldn't have Astana and Vienna tournament where I played really great level, maybe I would be a little bit less confident," he said.
"I'm confident I'm going to be able to do something big in the future. Just need to continue working. Going to be sad for one, two days, then enjoy my days off, then get ready for the next season."
