There has been sweating, dizziness and even the warning from Daniil Medvedev that a player could “die” in the hot conditions at the US Open.
With players again struggling with the heat on one of tennis’ biggest stages in temperatures around 35C on Thursday, BBC Sport looks at the impact on their bodies and what organisers do to protect them.
Light-headedness and nausea – what happens to athletes in the heat?
Medvedev and beaten opponent Andrey Rublev were physically and emotionally affected by the extreme conditions during their two hours and 48 minutes on court on Wednesday.
A person’s average body temperature is 37C but when athletes push themselves to the limit in high temperatures, heat exhaustion – when the body gets too hot – can occur.
Symptoms include increased breathlessness, cramp, light-headedness and nausea and if not treated properly by cooling the body down, heatstroke can set in and lead to a possible medical emergency.
To try to combat this during their quarter-final, Medvedev and Rublev sat under ice towels, took respite from the sun during lengthy bathroom breaks and hosed themselves with cold water whenever possible.
The excessive amounts of sweat produced by the searing heat also caused Medvedev an unusual problem, as he remarked he had “no skin left on his nose” because of the constant need to wipe his sweat-drenched face.
Britain’s Andy Murray, the 2012 US Open champion, based his training for the this year’s final Grand Slam around stationary bike sessions in his steam room – with the temperature set to 35C (95F) and 70% humidity – to try and simulate conditions.
In 2018, the conditions at Flushing Meadows were described by Hungarian player Marton Fucsovics as “dangerous” as five male players had to retire from their first-round matches because of heat-related issues.
The tournament five years ago was the first time organisers implemented an extreme heat policy in men’s matches as temperatures touched 38C (100F) and humidity levels were above 50% in New York.
Previously, the men’s ATP governing body had a discretionary rule for players competing in searing temperatures at the US Open, while the women’s WTA already had an extreme heat policy for its players set out.
Serb Novak Djokovic and opponent Fucsovics used the longer break between sets during their first-round tie in…