Rafael Nadal says he has no explanation for his big serving during the U.S. Open except for a change in his grip.
Nadal is the only player who has not been broken so far in the tournament. He hit a serve at 135 mph during his fourth-round match against Feliciano Lopez, likely the fastest of his career, following the 134 mph he hit in his second-round match against Denis Istomin.
"No, I wasn't on the gym," he joked in a courtside interview after defeating Lopez. "Seriously, I don't know. I think sometimes it's part of the confidence, the serve. It's true, I'm serving faster than ever."
Nadal is now tied for first in first-serve points won during the tournament, with 85%.
After his previous match, Nadal had said, "Seriously, I didn't serve very well in the previous tournaments. But I started to serve well the week before the tournament, a few days before the tournament start. I changed a little bit the grip, but that's all."