Djokovic suffered his second successive shock exit on red clay in quick succession after he was beaten by Briton Dan Evans in the third round of the Monte Carlo Masters last week, having failed to convert a barrage of breakpoints against Karatsev. The Russian will meet either Japan's Daniel Taro or Italian Matteo Berrettini in Sunday's final at Djokovic's tennis centre in downtown Belgrade by the Danube river.

Djokovic praised Karatsev after what he said was a forgettable evening. "Hats off to Karatsev, he was bold and deserved to win," Djokovic told an online news conference.

"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. "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."

Karatsev said: "This is definitely the most important victory of my career. At the Australian Open in Melbourne, I felt like I was playing against a wall but this is a different surface and I was focused."