World No 1 Aryna Sabalenka has spoken out against the inclusion of transgender athletes in women’s tennis, saying “I don’t agree with this kind of stuff in sport”.

In theory, the guidelines of the Women’s Tennis Association allow transgender athletes to participate as long as they have maintained a blood testosterone level below 2.5 nmol/l for the previous two years.

In practice, no examples of this happening have been observed in professional tennis in recent years, although the early transgender player Renée Richards did play at a high level on the WTA Tour from 1977 to 1981, before going on to coach Wimbledon legend Martina Navratilova.

Navratilova has become a staunch opponent of transgender inclusion in modern tennis – as indeed has Richards – and in June she told the BBC that “by including male bodies in the women’s tournament, now… a woman is not getting into the tournament because a male has taken her place”.

On Tuesday, this point was put to Sabalenka by Piers Morgan during an interview on his Uncensored channel. “That’s a tricky question,” Sabalenka replied. “I have nothing to do against them [the trans community] but I feel like they still got a huge advantage over the women and I think it’s not fair on women to face basically biological men.”

“It’s not fair,” the Belarusian repeated. “The woman has been working her whole life to reach her limit and then she has to face a man, who is biologically much stronger, so for me I don’t agree with this kind of stuff in sport.”

During the same interview – in which she sat alongside Nick Kyrgios to promote their upcoming “Battle of the Sexes” in Dubai on December 28 – Sabalenka was asked about recent comments from Marta Kostyuk, the Ukrainian world No 26, who had claimed in October that she was at a disadvantage against players like Sabalenka and this summer’s Wimbledon champion Iga Swiatek because they have a higher level of testosterone than her.

“All I hear here is just excuses,” Sabalenka replied. “It’s actually quite funny, because she [Kostyuk] is a strong girl, and she probably has more muscles than I do and she looks fit and strong, and I think that [a difference in testosterone levels] is not the case in all the matches she lost against top players.”

One other area of controversy that came up in the interview was the apparently unequal treatment shown to high-profile tennis players who have tested positive for banned substances.

There has been backstage unrest within the sport over the way that Swiatek and men’s world No 2 Jannik Sinner both received relatively light sentences on grounds of contamination, after they each returned a positive test in 2024. Meanwhile, lesser names have often had to serve lengthy provisional suspensions before their cases were heard.

Sinner negotiated a three-month ban for the offences after the International Tennis Integrity Agency (ITIA) had originally found that the Italian bore no fault or negligence for the presence of the steroid in his system. In Swiatek’s case, the ITIA issued a one-month ban after ruling that the player’s level of fault was at the lowest end of the range with “no significant fault or negligence”.

Sabalenka, 27, sounded as though she shared the general sense of scepticism about the whole process, but eventually settled for a vague statement of unease.

“With Iga, they counted her weeks [of suspension, which ran to one month] off somehow randomly,” Sabalenka said. “‘OK, we count them during the China swing, and then you can play the [WTA] Finals, and then we take a couple of weeks during the next season.’ I think we should have the same treatment for every player.”

Sabalenka and Kyrgios – the 30-year-old who is ranked at No 672 after many months of absence through injury – are to contest their match over three sets in Dubai. Playing conditions state that each player will have just one serve per point, while the court will be nine per cent smaller on Sabalenka’s side. Live coverage is to be available on BBC Two.