Billie Jean King congratulates Novak Djokovic on 90th career title at Astana Open

Novak Djokovic picked up from where he left off, grabbing back-to-back titles in a two-week span for a 90th trophy at the Astana Open Sunday night.

Djokovic won Wimbledon in July before being forced to take a near-three month break due to his unvaccinated status, which kept him from playing a number of tournaments, including last month's US Open.

But the long layoff did not seem to bother Djokovic in the slightest, who, after participating in the Roger Federer-led Laver Cup team event two weeks ago, went on to take the titles in Tel Aviv and in Kazakhstan.

Congratulatory messages poured in for the Serb on social media, including one from tennis legend Billie Jean King.

King, who herself won 67 singles titles in her career, took to Twitter to celebrate Djokovic's milestone.

"Congratulations to @DjokerNole on winning his 90th career title in Astana!" posted Billie Jean King.

Djokovic beat Cristian Garin, Botic van de Zandschulp, Karen Khachanov, Daniil Medvedev (via retirement) and Stefanos Tsitsipas en route to the Astana trophy.

Novak Djokovic welcomes "restart" to the season

Stefanos Tsitsipas was the runner-up to Novak Djokovic in the Rome Masters last May.

Novak Djokovic made it three in a row after winning Wimbledon, Tel Aviv and Astana.

But the last two victories came after a near-three-month break that Djokovic considered a "restart" to his season, where he played sparingly due to his continued refusal to take the COVID-19 jab.

"I could not ask for a better restart of the season. I’m super pumped and motivated to end the season as well as I have done these past couple of weeks," said Novak Djokovic during his post-match on-court interview.

Stefanos Tsitsipas, who remained unsuccessful in ATP 500 finals in his ninth try, commended Djokovic after bowing to the Serb for the seventh straight time. Djokovic now holds a commanding 8-2 lead in their head-to-head.

"This is not the first time, again, in the final. I would like to congratulate you. I would never stop congratulating you. It feels like it will keep happening non-stop," said Stefanos Tsitsipas, who has now lost all five finals he has contested against Novak Djokovic, in his runner-up speech.

"Unbelievable performance. You're extremely accurate, an extreme professional out on the court," added Tsitsipas.

The Astana trophy was Djokovic's fourth of the year after also reigning in Rome last May against the same foe in Tsitsipas. Djokovic played just his ninth tournament this season, reaching the finals five times. His only finals loss came against Andrey Rublev in his home tourney in Belgrade last April.