Serena Williams has been hailed as the ‘greatest of all time’ by reality star Kim Kardashian after her US Open heroics.

The tennis superstar, 40, kept her dreams of a seventh Flushing Meadows title alive after beating No2 seed Estonian Anett Kontaveit.

Kim Kardashian paid tribute to ‘GOAT’ Serena Williams after her US Open victory Credit: kimkardashian/Instagram

Kim K and Serena’s friendship goes back nearly 15 years Credit: Getty

The reality TV star used to work organizing celeb’s closets – including Serena’s Credit: Splash News

Kardashian revealed Williams’ surprising love of karaoke Credit: Corbis

Williams’ victory means she is still in the hunt to equal Margaret Court’s incredible record of 24 Slam singles titles.

There was another sporting great in attendance in Queens as golf icon Tiger Woods roared on Serena from the stands.

And entertainment royalty was also tuning in, with Kim K taking to Instagram to declare her admiration for the six-time US Open champ.

Sending her 329m followers a picture of Serena serving during her win, she simply captioned it: “GOAT [Greatest of all time]”

Kim and Serena’s friendship goes way back with the pair reportedly close pals for almost twenty years.

Their bond began before Kardashian became a global superstar and had a job organizing and cleaning out different celebrities’ closets.

One of her clients was Serena, with the pair hitting it off immediately.

Kardashian attended Williams’ wedding with Reddit co-founder Alexis Ohanian in November 2017.

And she praised the “real” connection the pair have after the star-studded New Orleans bash.

Kim revealed to Vogue in 2017: “I’ve known Serena for so long and am so happy she’s found her prince.

“From the moment she told me she met Alexis in Rome, it was like she’s been so happy and has this light about her that is so special to see.

“You just know it is so real. He makes her so happy and that just makes her friends happy.”

While the reality TV superstar says that Serena is one of her closest confidantes.

Kim K continued: “Serena’s the girl you can call and say anything to.

“She’ll never judge you, and she’s never too busy for you.

“Oh, and she can keep a secret.”

Kardashian even went on to reveal just how Serena likes to recharge away from the court.

She said: “She is obsessed with karaoke, which personally is my biggest fear in life.

“I remember a dinner in San Francisco before a DNC fund-raiser.

“Serena sang, Obama sang, Kanye sang. It was legendary.

“She gives herself those moments — it’s how she recharges.”

Kardashian took to Instagram to wish Serena a happy 40th birthday earlier this year and their bond looks as strong as ever.

She wrote: “Happy Birthday, Serena Williams. Love you always!!!!”

Williams will now face Ajla Tomljanovic in the third round at Flushing Meadows, with the match set for Friday, September 2.

Kardashian was a guest at Serena’s wedding with husband Alexis Ohanian Credit: EPA