Naomi Osaka has condemned Jelena Ostapenko for attacking Taylor Townsend over her 'education' and 'class' at the US Open, claiming it was 'one of the worst things you can say to a black tennis player'.

Ostapenko, 28, is at the center of a racism storm after her explosive rant towards black American player Townsend, who defeated her in their second round women's singles match on Wednesday.

After the loss, the hot-headed Latvian fumed over what she perceived as a lack of etiquette on the court when her opponent failed to apologize for a shot that clipped the net on its way over, telling her when they shook hands that she has 'no education and no class'.

Hours later Ostapenko took to social media to reveal she has been hit with accusations of racism, which she vehemently denies. 'I was NEVER racist in my life and I respect all nations of people in the world, for me it doesn't matter where you come from,' she wrote on Instagram.

And Osaka, who is of black and Asian heritage, was quizzed on the controversy after her second-round US Open win over America's Hailey Baptiste on Thursday.

'Yeah, I saw that part obviously. It's been on the TV like every 15 minutes,' the Japanese star said when asked if she was aware of Ostapenko's tirade.

'I think obviously it's one of the worst things you can say to a black tennis player in a majority white sport. And granted, I know Taylor and I know how hard she's worked and I know how smart she is, so she's the furthest thing from uneducated or anything like that.'

Ostapenko has developed a reputation for having a temper on the court over the years, having let the red mist descend on several occasions in the past.

Osaka continued about the world No 25: 'If you're genuinely asking me about the history of Ostapenko, I don't think that's the craziest thing she's said. I'm going to be honest.

'I think it's ill timing and the worst person you could have ever said it to. And I don't know if she knows the history of it in America.

'I know she's never going to say that ever again in her life. But yeah, it was just terrible. Like, that's just really bad.'

Ostapenko returned to action less than 24 hours after her altercation with Townsend, taking to the court again at Flushing Meadows for her women's doubles first-round match alongside teammate Barbora Krejčíková.

Despite her fiery attack on a home player the day prior, she surprisingly avoided any boos as she walked out alongside Krejčíková in New York, with some in the crowd even cheering her name when she was introduced before the match. 

Earlier on Thursday, world No. 1 Aryna Sabalenka hinted that off-court personal issues were behind the rant that left Ostapenko forced to deny claims of racism, adding that she hopes her fellow Eastern European will 'one day figure herself' out.

'I actually spoke to Jelena after the match,' said the Belarusian. 'During our conversation, I didn't know what happened. I have to say that she's nice, she just sometimes can lose control. She has some things in life to face and some struggles.

'I was just trying to help her to face it more in a mature way, to settle down and be someone she could speak to and just let it go.

'I think she sometimes can lose control over her emotions, which is pretty tough.

'I really hope one day she will figure herself out and handle it much better.'

Townsend was also asked in her post-match press conference if she believed there was any racial undertones to Ostapenko's comments.

'That's something that you're going to have to ask her,' she said. 'I didn't take it in that way, but also that has been a stigma in our community of being not educated and all of the things when it's the furthest thing from the truth.'

Townsend continued: 'I can't speak on what her intentions were... saying I have no education and no class, I don't really take that personally, because I know that it's so far from the truth.... whether it had racial undertones or not, that's something she can speak on.'