Caroline Wozniacki (L) impersonates Serena Williams

Rory McIlroy's girlfriend, 22 year old tennis star Caroline Wozniacki, has discovered that mocking other women's appearances isn't the laugh getter she thought it was.

According to the Irish Independent, Wozniacki, in what she thought was a light hearted swipe at tennis pro Serena Williams, stuffed towels into her top to balloon her bust and her behind during her tennis match against Maria Sharapova on an exhibition tour in Sao Paulo.

The reaction of her partner Rory, who was at her game, is unknown but the internet erupted in anger almost immediately. And it's possible that Wozniacki regretted her decision on the day too, because she lost to Sharapova in straight sets.

Now the young Dane has now been accused of racism on the court of public opinion that is the world wide web.

On Tumblr, one blogger reportedly wrote: 'This isn’t 'harmless fun' as one article described it. It's racist. Out and outright racism. Mocking and making fun of the bodies of black women for a laugh? Real funny, stupid white girl. Real real funny.'

Another blogger wrote: 'It may have been done in 'jest,' but I love how people can can turn a black woman’s body and sexuality into a caricature. However, we should not have the autonomy to celebrate any successes of our own.

While on, an article read: 'Given the history and current-day context of racialized standards of beauty, and the hypersexualization of people of color, when a white woman makes fun of a black woman’s body, especially in a way that hypersexualizes her and draws on the stereotype of black women’s big butts, it’s racist.'

Wozniacki told a press conference after the game that she was performing an impression of her friend and fellow tennis player Serena Williams.

She said: 'I really love the crowd here, they're open and they have a lot of fun.'

This was not the first time Wozniacki imitated the American tennis icon, last year she imitated her as well.