The US Open is less than a week away and the countdown to Serena Williams' retirement has started.

Following an emotional letter announcing her decision to "evolve away from tennis", it seems likely that the final Grand Slam of the year will be the court legend's swan song.

However, fellow tennis icon Martina Navratilova doesn't believe a fairytale ending is on the cards for Williams.

The 23-time Grand Slam champion started to say her goodbyes to the sport at the National Bank Open earlier this month.

It was her first match since releasing her farewell announcement with Vogue and the star was left in tears following her second round defeat to Belinda Bencic.

An emotional Williams left the court to a standing ovation from the adoring Canadian crowd.

The 40-year-old then played at the Western and Southern Open, a tournament she has won twice in her career, where she lost to Emma Raducanu in the first round.

Her Cincinnati appearance was her penultimate build-up match ahead of the US Open, after which Williams will likely hang up her racquet.

Serena Williams of the United States wavess to the crowd as she leaves the court after losing to Belinda Bencic of Switzerland during the National Bank Open, part of the Hologic WTA Tour, at Sobeys Stadium on August 10, 2022 in Toronto, Ontario, Canada. (Photo by Vaughn Ridley/Getty Images)

Navratilova empathised with the former world number one and reflected on how difficult it was for her when she called time on her career.

"It's hard. When I retired in '93 I told the press it was my last year which was a mistake because every single tournament was a freaking tear-jerker," she told Reuters.

"Serena did it her way, which was announcing in a very glamorous way on Vogue magazine, but then she is not accepting the losses, she is not accepting what comes with it which is saying goodbye."

Serena Williams of The United States plays a smash in her Ladies' Singles final against Simona Halep of Romania during Day twelve of The Championships - Wimbledon 2019 at All England Lawn Tennis and Croquet Club on July 13, 2019 in London, England. (Photo by Shaun Botterill/Getty Images)

The 18-time Grand Slam champion then predicted more of fizzle than a bang when it comes to the end of Williams' iconic career.

Navratilova admitted she doesn't see "a Cinderella happy ending where she [Williams] wins" at this year's US Open.

"The way she has looked, it doesn't look like she is going to make a miraculous comeback and win the tournament. And with the stress of knowing this is likely your last tournament it doesn't help.

"But if anyone can overcome it would be Serena."

Indeed, Williams has struggled with her form and has been hampered with injuries which have affected her performances on the court.

A record-equalling 24th Grand Slam title would, of course be the dream curtain fall for Williams, but the odds are against her as she prepares to take on Flushing Meadows for what will more than likely be the last time.