Did Serena take a sly dig at Sharapova?

Serena Williams has seemingly taken a cheeky dig at long-time rival Maria Sharapova on social media.

In the hours leading up to Sharapova's heavy defeat at the hands of Angelique Kerber, former World No.1 Serena responded to a Twitter follower's post with a very interesting reply.

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“Kinda want Sharapova to win tomorrow," the Serena fan tweeted.

However Serena wasn't as enthusiastic, with the 36-year-old replying with the following emoji.

The closed-mouth, wide-eyed face usually suggests someone doesn't really agree with what someone has said, and it was enough to make American tennis writer Ben Rothenberg take notice.

"And they say it's not a rivalry," he tweeted, clearly not convinced by Serena and Sharapova's downplaying of their ongoing feud.

Last year Sharapova lifted the lid on the explosive sledge that kickstarted her not-so-friendly relationship with Serena.

Sharapova had just upset Serena in the 2004 Wimbledon final when she walked in on the American "bawling" in the locker room.

"I got out as quickly as I could, but she knew I was there," Sharapova wrote in her autobiography.

"People often wonder why I have had so much trouble beating Serena; my record against her is 2 and 19. To me, the answer was in this locker room.

"I think Serena hated me for being the skinny kid who beat her, against all odds, at Wimbledon. But mostly I think she hated me for hearing her cry.

"Not long after the tournament, I heard Serena told a friend – who then told me – 'I will never lose to that little b**** again'."

Sharapova said her 2004 victory actually spurred Serena to greatness.

"Serena and I should be friends; we have the same passion. But we are not. I think, to some extent, we have driven each other. Maybe that’s what it takes.

"Only when you have that intense antagonism can you find the strength to finish her off. Who knows? Someday, when all this is in our past, maybe we’ll become friends."