Andy Murray has admitted that playing under hot weather conditions at the Miami Masters is not easy.
The 26-year-old Briton made the comments following his 6-4 6-1 victory over Feliciano Lopez in 73 minutes in the third round.
"It's not always that easy to feel comfortable against him because there is not loads of rhythm with the way he plays, but I moved well, returned well," BBC Sport quotes Murray as saying.
"I don't know how hot it was, but when we came over at like 9.30pm it was already 80 Fahrenheit (23 Celsius) and it was extremely humid.
"I've played a few matches here where it's been very, very hot, but it doesn't always stay like this for a few days in a row in March. They are not easy conditions."
Murray will take on Jo-Wilfried Tsonga in the fourth round.