Juan Martin Del Potro defeated Rafael Nadal to book a final place against Novak Djokovic on Sunday.
Del Potro, 29, was leading 7-6 (7-3) 6-2 when Nadal retired because of a knee problem.
Nadal twice needed medical attention before retiring
“It was difficult for me to keep playing. I was in too much pain,” Nadal said
“It was one player playing and one on the other side of the court. I hate retiring – but to stay one more set out there playing like that is too much for me.”
Del Potro said after his victory against Nadal
“It is not the best way to win a match. I love to play against Rafa because he is the biggest fighter in the sport,” said Del Potro.
“I don’t like to see him suffering like today. I am sad for him. I think the key to the match was the first set.”