Dominic Thiem is surprised that he became nervous in the semi-final of the ATP Finals against Novak Djokovic on Saturday.

The Austrian thought his victory at the US Open in September would make him more relaxed at decisive moments in a match.

He did win.

"This was a mental fight. The tiebreak of the second set was so exciting. I thought that after my first Grand Slam title in New York I would be a bit quieter at such moments, but no. I was just as nervous as before" , Thiem said after the party in London.

The 27-year-old Thiem was able to step off the track against Djokovic after almost three hours: 7-5, 6-7 (10) and 7-6 (5).

The number three in the world already received four match points in the second set, but did not use them.

In the tiebreak of the third set it worked on his sixth power point.

"All the games here at the ATP Finals are so

close

, but that's because the best tennis players in the world face each other here," Thiem continued.

"That's why I'm so incredibly happy to have won. I'm now getting ready for tomorrow's final."

Novak Djokovic congratulates Dominic Thiem.

(Photo: Pro Shots)

Djokovic: 'Thiem from 0-4 really unbelievable'

Djokovic didn't blame himself after the match and was full of praise for his opponent from Austria.

Due to the defeat, the Serbian remains on five titles in the ATP Finals, one less than record holder Roger Federer.

"What Dominic did in the tiebreak of the third set from 0-4 was really unbelievable", said Djokovic, who saw Thiem score six points in a row in the decisive tiebreak at that position.

"He did everything right. I can only congratulate him, because I didn't even play bad there."

"I was in all points in the rally and didn't play forcibly, but he overcame me and was just great. What can you do about it?", Said Djokovic, who closes the 2020 calendar year as number one in the world despite his elimination.