Marta Kostyuk claims Aryna Sabalenka and Iga Swiatek’s ‘testosterone levels’ make them better

The World No 27 was asked to explain what separates her from the players at the top of the rankings

World No 27 Marta Kostyuk has claimed Aryna Sabalenka and Iga Swiatek’s “higher testosterone levels” make them better players.

The 23-year-old Ukrainian offered the explanation that the size of Sabalenka and Swiatek’s bodies is a factor in what separates them from her in the rankings.

In a recent interview with Tennis365 in Wuhan, Kostyuk said: “With Iga [Swiatek], when I have played her, I wasn’t ready to play her at all. I played her over a year ago. With Aryna [Sabalenka], I don’t know, to be honest. When I look at these players, I have my own skills, but at the end of the day, they are all much bigger than me, much taller than me, much stronger than me.

Kostyuk has lost all four matches she has played against the World No 1 Sabalenka (Getty Images)

Kostyuk added: “We all have different biological structure. Some have a higher level of testosterone, some have lower. I know players who are good players who have higher levels of it. It’s just natural, they don’t take anything. I’m sure of that. It’s just the biology of their body. Obviously, that definitely helps.

“I’m trying to see how I can beat these players with the tennis skills I have, but I have to work more than they have to win the points. I need to run a lot more. I am much more of an athletic player. I cannot just hit the ball hard, sweeping players out of the court with my power. I cannot make myself suddenly 10kgs bigger or five centimetres taller, so I have to find ways to use everything I have at 100 per cent. For other players, they have more of an advantage in other things.

“This is just the way I am. My body, I’m really small. I look at the pictures when we are on the court and I look so much smaller than everyone. I cannot be bigger. It’s just part of the sport. I think it’s a very cool challenge, if I think about it. I really have to sit down and think, okay, what can I do to get make better against these players. I’m sure there are many, many things I can do better."

Kostyuk is listed as 5ft 9in on the WTA’s website - the same height as World No 2 Swiatek and just two inches shorter than the the World No 1 Sabalenka, who is 5ft 11in. World No 3 Coco Gauff is also 5ft 9in, while the World No 6 Jasmine Paolini has reached grand slam finals at Wimbledon and Roland Garros at 5ft 4in.

Kostyuk is listed at the same height as Swiatek (Getty Images)

The Ukrainian has lost all four matches she has played against Sabalenka - including two close matches at the Madrid Open and Italian Open this season - and all three she has played against Swiatek, with their latest meeting coming in Cincinnati in August 2024.

Kostyuk acknowledged that mental strength also plays a part and admitted that she does not find it “so easy” to play without doubt. She added: “Their confidence is just different. I have played some close matches against Aryna and you see how she plays the break points. She just doesn’t care. She has no doubt that she will save them. She hits a big serve and hits the forehand. No doubt. She is No 1 in the world, she has played a lot of finals and she has that confidence.”

This article was amended on 24 October 2025. It previously stated that Kostyuk had been asked if she felt "intimidated" by players like Sabalenka and Swiatek. However, she had not been asked that question in her interview with Tennis365. The outlet subsequently qualified its own article to say that they had “inserted” that question and had not in fact asked her this. We have also added another sentence which was omitted from the initial Tennis365 article, in which Kostyuk stated that she was not suggesting her rivals had taken anything to change their testosterone levels.