LONDON (AFP) - Novak Djokovic took a swipe at fans at the ATP Tour Finals after claiming he was distracted by comments from the crowd during his semi-final win against Kei Nishikori on Saturday.

Asked why he had sarcastically clapped his racquet when the crowd at London's O2 Arena cheered after he was broken by Nishikori early in the second set of his 6-1, 3-6, 6-0 victory, Djokovic claimed he had been taunted by some individuals in the sold-out 17,500 stadium.

The world No. 1 gave only a cursory wave to the fans at the end of the match and broke the tennis custom of signing his name on a television camera, instead marking the screen with only a dot.

Defending champion Djokovic, who will face Roger Federer or Stan Wawrinka in Sunday's final, explained his grumpy behaviour by saying he feared he might have lost the match because of the incident as it affected his concentration.

"There were some individuals that were going over the line throughout the whole match, some provocations that I usually don't react on, but I did. It was my fault," Djokovic said.

"I lost concentration. I lost the break because of that. I allowed myself to be in the situation to lose the set, maybe even lose the match.

"I should have let it go. But, you know, when you tolerate once, twice, three times, four times, we're all humans, you react.

"As I said, everybody is different. Everybody has a choice what they do. I just was not happy with the way that has influenced me and my game after that.

"But it's the way it is. I'm just glad that I overcame that. It's a lesson. Hopefully, tomorrow it will not happen.

"Generally, it was my fault and I should know better. At the end of the day, I cannot blame the crowd.

"The crowd has a right to do what they want, to cheer for whoever they want."