Daniil Medvedev reached the US Open semi-finals after beating Andrey Rublev in hot and humid conditions that he said would cause a player to "die".
The third seed appeared to struggle with his breathing but won 6-4 6-3 6-4 against his fellow Russian.
"One player is going to die and you are going to see," he said into a camera during the match in New York.
Medvedev won his only Grand Slam at the US Open in 2021 after beating Novak Djokovic in the final.
Rublev has now failed to make the semi-final of a major in nine attempts.