Novak Djokovic claimed his 90th ATP title after beating Stefanos Tsitsipas in the final of the Astana Open in Kazakhstan.

Tsitsipas lost his serve in the eighth game of the first set before his rival went on to take the opener.

Djokovic later broke Tsitsipas in the fifth game of the second set and took the match on his third match point.

The victory guarantees the 35-year-old a spot at the 2022 ATP Finals.

Tsitsipas has finished runner-up in each of the nine ATP Tour finals he has played.

In the Japan Open, Taylor Fritz beat fellow American Frances Tiafoe 7-6 (7-3) 7-6 (7-2).

Fritz was in a week-long quarantine in South Korea after contracting Covid-19 and flew to Tokyo on Wednesday on the morning of his first match of the tournament.

His victory means he will break into the top 10 of the men's rankings for the first time on Monday with a new ranking of eight.

"First off, I want to congratulate Frances on a great week. I mean, he's been on fire recently and I had to play my absolute best to beat him today," Fritz said.

"We've spent a lot of time together the last couple weeks, he's one of my really close friends, and I'm sure it's not going to be the last time we play for a big-timer."