‘I believed in myself’: Russian tennis ace Karatsev on epic upset against Djokovic to shock ‘angry’ world No.1 in Serbia (VIDEO)

Russian tennis sensation Aslan Karatsev has described his win over Novak Djokovic on the world No.1's home soil as the "most significant" of his career, beating the all-time great in an epic marathon encounter at the Serbia Open.

Djokovic was a huge favorite to repeat his Australian Open final triumph over Karatsev in his homeland and win the tournament, only to be stopped in his tracks in dramatic fashion in the semi-final in the longest ATP Tour match of 2021 so far, clocking in at three hours and 26 minutes despite only spanning three sets.

That was largely because Karatsev heroically saved 23 points out of 28 against his own serve, thwarting the 18-time Grand Slam champion to win 7-5, 4-6, 6-4.

Karatsev fell narrowly short in the final, losing on a third-set tie-break to world number 10 Matteo Berrettini, but his displays were another sign of the rising status of the world number 27 who was ranked at 253 just a year ago.

"I produced great tennis and can't say much about what was going through my mind during those numerous break points I had to play against," he said afterwards, telling reporters to pay more attention to the Challengers tour he was a part of for so long on his way up the ranks.

"You have to play aggressive tennis against a rival like Novak; if not, it feels like you are hitting against the wall, as everything goes back to you and forces you to run a lot.

"I stepped on the court to beat Novak. I believed in myself and promised that I would give my best on every ball.

"My main goal was to take the ball early and stay aggressive. I want to reach the top 20, and then I can set other goals. To achieve that, I will have to play at my best in every tournament.

"I spoke with my coach about fighting for every point, which was one of the key elements of my success. It's the most significant victory of my career, with Novak being world number one. I'm happy with how I fought and left my everything on the court in a long match."

The shock defeat was another setback for Djokovic after he lost to the man ranked immediately ahead of Karatsev, Briton Dan Evans, in the round of 16 at the Monte-Carlo Masters earlier this month.

“When I lose, I can only be angry with myself, not with the opponent,” he said. “He was better.

"I will probably not be able to recollect all the memorable rallies in this match because I lost. I am not happy with my performance. I put up a fight but he delivered great shots every time he needed to.

“He scored when he should have. I have to wonder why I lost, but whoever won, I have to congratulate him in the end.”

Karatsev continues to be asked about his seemingly sudden surge to the top of the sport. “It’s not just happening right now – there is [a lot of] work that was done before [this year],” the 27-year-old explained, adding that three-set matches had given him "more and more confidence".

“I had some injuries before and some troubles, and now we’re doing a good job with my coach. It’s been two-and-a-half years and it’s just paying off in 2021.

“It’s not like it’s coming all of a sudden from nowhere. It’s coming from the hard work every day, and it’s a long process. You have to be there every day and work hard.

"You have to work and be in practice every day and improve your game, mentally and physically. It’s not like it’s all arriving right now and that’s it."

He admitted that the exertion of his seismic win over Djokovic could have taken its toll against Berrettini.

“I wasn’t there in every point, but all credit to him – he played fantastically in the end and served really well. I couldn’t really serve or go for the big shots, going around the forehand.

“At the tie-break, he was serving unbelievably. I wasn’t there. There were some points where I wasn’t there, and he did well in the tie-break as well, pushing me to the limit.

"I was unlucky at times, it all came down to one or two shots but I had too many ups and downs throughout the match."