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 beat his fellow Russian 6-4 6-3 6-4 on Wednesday.
"One player is going to die and you are going to see," he said into a camera during the match in New York.
Medvedev faces Carlos Alcaraz next after the defending champion beat Alexander Zverev 6-3 6-2 6-4 .
Spain's Alcaraz, 20, saw off five break points on his way to an efficient victory over the German 12th seed.