Alexander Zverev claims stars are putting their health at risk as Medvedev wades into row

The debate over changing tennis balls is rumbling on at this week's ATP Finals.

Each week, players head to another tournament and likely have to play with a new brand of ball even if the court surface stays the same.

Alexander Zverev has now claimed players' health is at risk after doing "research" into the issue while weighed in with a solution.

Everyone from Novak Djokovic and Emma Raducanu has at each tournament. Players have often argued that the changes mean the balls get fluffier and heavier faster, slowing down the game and leaving them at risk of getting injured.

It's become one of the biggest talking points in recent years and Zverev has now explained why he believes the quality has gotten worse.

"Yeah, the ball is a big subject. I actually, because I'm on the players council, the ball was a very interesting subject to me, as well. I kind of went into search mode a little bit. I asked companies and I asked the production of the tennis balls," the world No. 2 said.

"Since Covid, all the companies, it's not only one company, so Dunlop was always the best tennis ball kind of, but they've gotten a lot worse. I always loved the Penn balls. They've gotten a lot slower.

"The reason being, because of Covid, the companies tried to cut costs and they're using a different rubber material now. They're using a different material for the tennis balls, which makes the tennis balls between 30 per cent and 60 per cent slower on average compared to what it was before Covid."

The recent Paris Masters champion says the issue is true for every brand of tennis ball. Zverev continued: "What happens now with the tennis balls is that the air and the pressure leaves the tennis ball because of the material.

"The material doesn't keep it inside. It's not only that the ball fluffs up, but actually the air and the pressure of the tennis ball drops drastically. That's why a lot of players now have elbow issues. A lot of players have wrist issues. That was not the case about 10, 15 years ago."

The 27-year-old also raised fears over the health of players. "I don't know if I explained it well or understood. I was very interested in the tennis ball," he added.

"I don't have a reason to complain. I'm No. 2 in the world. I've had a great season. I'm not complaining because of results. I just think in long-term, long run, players' health is a big issue with the tennis balls we have at the moment."

After hearing of Zverev's investigation, Medvedev admitted it made sense. The former world No. 1 has consistently argued that the balls are making the game slower and even brought it up after his defeat on Sunday.

"Some players like me that are not satisfied with the balls, they're saying it's exactly after Covid that it changed. That's a little bit my feeling. 2022 was my worst year," the Russian said on Tuesday.

"I had to change strings for softer ones so my ball goes faster through the air because I basically couldn't hit a winner anymore. It worked well.

"This year I changed for softer ones. On clay and grass, it was tougher to play. Anyway, it became a little bit of a mental hustle. Today I changed again and it was well. That's exactly what he explained is exactly what I feel, that the ball dies in the air."

Medvedev now wants to see the manufacturers "use better materials" if Zverev's claims are true. But he also believes tournaments should vary the balls they use. "There should be variety 'cause some players will benefit from these balls, and it's okay for me," he added.