Staying on court was too much for me: Nadal

World number one Rafael Nadal, who had to pull out of the semi-final of the ongoing US Open owing to a knee injury, said that although he hates to pull out, staying on the court for another set seemed too much for him.

"I hate to retire, but to stay one more set out there playing like this was too much for me," ATP quoted Nadal, as saying.

The 32-year-old said that he had some issues with his knee during the tournament, and when the pain resurfaced during the match, he realised that it was not going to improve any sooner.

"I had some issues during the tournament. Today at 2-all in the first I felt it again. I said to my box immediately that I felt something in the knee. After that, I was just trying to see if it could improve during the match. But no, it was not the day," Nadal said.

"I waited as much as I could. You could imagine it was very difficult for me to say goodbye before the match finish. But at some point, you have to make a decision. It was so difficult for me to keep playing that way, having so much pain. It was not a tennis match at the end. It was just one player playing, the other one staying on the other side," he added.

Admitting that this phase is tough for him, the Spaniard assured that he would keep working hard to make a comeback.

"It is tough, these moments, but at the same time, I am going to keep working hard to have these opportunities. I know the things are going the right way. I am playing well. I am enjoying on the court. I am having a lot of success. I am very competitive at the age of 32. I am here fighting for titles, fighting for the first position of the ATP Rankings," he said.

Nadal was trailing the semi-final match 6-7, 2-6 against Juan Martin del Potro when he decided to retire due to a niggling knee injury.