Rennae Stubbs, a former coach of Serena Williams, has hit back at online abuse that she received from fans of Novak Djokovic after they perceived a tweet of hers as a slight against the player.

23-time Grand Slam champion Djokovic fought a long and difficult battle against world No. 1 Carlos Alcaraz in the final of the Cincinnati Open earlier this week. Although the Spaniard started out well, the Serb used his experience to prevail and win the match 5-7, 7-6(7), 7-6(4).

The final lasted three hours and 49 minutes, making it the longest Best of Three ATP Masters 1000 final in history. After the match, many were quick to praise the performance of the two players, with Stubbs taking to social media to call the final 'unbelievable.'

However, Stubbs also pointed out what she thought could be a potential missed "let" call on championship point.

"Unbelievable match! Unbelievable but I’m fairly certain there was a let on MP [match point]! Take a listen and watch Carlos reaction. Not taking it away from Novak, what an effort but man sucks if it’s true," Stubbs wrote on X, formerly known as Twitter.

Although the Australian made it clear that she wasn't trying to undermine Djokovic, many of his fans still took issue with the tweet, calling her "Stupid" and "sh*t".

Stubbs has since hit back at the comments, posting a screenshot of a couple of them on her Instagram story. The 52-year-old captioned it:

"Here is your routine everyday @djokernole fan!! This is 2 of about 200 in the past 24 hours."

Stubbs also responded directly to some fans on Twitter who were criticizing her claim, one of whom said:

"Shame on you! If it had been a let, it would have been called by the machine and the umpire. You just cant stand the fact that Novak won the match!" to which Stubbs replied:

"Calm the farm! It has nothing to do with who won or who lost, i would have said the same thing if it had been Novak…. Also do u know how many let’s get missed!?? I played a few matches in my day AND it happened more then u realize. So relax buddy!"