Andrey Rublev fought back from two sets down in brutally hot conditions to beat Arthur Rinderknech and reach the US Open third round.
Sixth seed Rublev looked down and out at the end of the second set and was struggling physically and mentally in 33C heat.
However he persevered, only managing to lift his arms above his head in celebration after a draining 4-6 5-7 6-1 6-2 6-2 win in four hours and six minutes.
A heat warning is in place in New York, with both Rublev and Rinderknech using ice packs and fans to try to cool down.