NEW YORK -- The slips and slides of the soft clay have been replaced by the squeaks of sneakers on the hard courts.
Nobody is handling the switch better than Rafael Nadal.
Nadal improved to 16-0 this year on the hard surface Monday, defeating American Ryan Harrison 6-4, 6-2, 6-2 in the first round of the U.S. Open.
"It's difficult to analyze now," Nadal said, when asked if he's playing the best hard-court tennis of his career. "I am playing well. Happy the way I was playing. I don't know if it was the best or not, but it was very good because I was able to win."
The victory in front of a half-full Arthur Ashe Stadium marked the first for second-seeded Nadal on any Grand Slam surface other than clay since the first round of Wimbledon in 2012.
Since then, Nadal has fallen to Lukas Rosol at the All England Club, withdrawn from the 2012 U.S. Open (knee) and 2013 Australian Open (stomach ailment), won the French Open and fallen to 135th-ranked Steve Darcis in the first round of this year's Wimbledon.
Nadal answered that unexpected loss with 11 straight wins, all on hard court, to improve to 16-0 on the surface this season. He won titles at Montreal and Cincinnati in the lead-in to the U.S. Open, which he won for the only time in 2010.
"We go day to day," Nadal said. "Two tournaments before winning is great for my career because both tournaments are very important ones. But that (doesn't) mean I will play great here. That means that I am doing the right things."
Harrison won't argue that point.
The 21-year-old American got bullied around the court by Nadal, who hit 28 winners and forced Harrison into 32 errors.
About the only thing to slow Nadal was a 15-minute break caused by a brief spit of rain that began just as Nadal had broken to go up 2-1 in the second set. The players stayed on the court and when they resumed, Nadal won 10 of the next 13 games.
Serving down 2-0 in the third and facing break point, Harrison followed a 131-mph serve into the net and put a volley deep into the corner on Nadal's backhand side. But Nadal answered with a clean passing shot and Harrison walked toward the sideline for the changeover and spiked a ball into his chair.
"From what I see, and what I gather, these top guys are really, really good at peaking at the slams," Harrison said. "They know how to get their best out of it."
Harrison, meanwhile, keeps getting the worst of these Grand Slam draws.
Ranked 97th and still looking to make his first decent run in a major, he has drawn Nadal once, Juan Martin del Potro once, Andy Murray once and Novak Djokovic twice in the first or second round of four of the last eight majors. He's 0-5 against them, 4-3 against everyone else.
The Nadal match was never close, but Harrison said he isn't losing hope.
"If you're 30 years old and you've only got a number of Slams left, then maybe you're upset with it," Harrison told The Associated Press on Sunday, when asked about his draw. "I'm 21. I'm excited. Every single time I get to play a match like this, it's hard not to be excited. ... And if I don't want to play the top guys in the first round, then that's kind of an incentive to get seeded."
AP Tennis Writer Howard Fendrich contributed to this report.