Five-time champion Roger Federer breezed into the US Open second round with a routine victory over Japan's Yoshihito Nishioka at Flushing Meadows.
Federer, 37, needed one hour and 52 minutes to win 6-2 6-2 6-4 in the night session on Arthur Ashe Stadium.
The Swiss great hit 56 winners compared to just 17 from his 177th-ranked opponent.
The 20-time Grand Slam winner will play France's Benoit Paire in the second round in New York.
"I'm very happy with how I played tonight. It is particularly tough for us Europeans because we don't get this type of humidity. You are sweating so much you don't know what has hit you," Federer said.
"It is tough so you are happy when you survive a day like this."
Federer, playing in the US Open main draw for the 18th time, is bidding for an eighth men's final in New York - which would equal the record set by Pete Sampras and Ivan Lendl.
The Swiss dominated the tournament between 2004 and 2009, winning 41 successive matches before losing to Argentina's Juan Martin del Potro in the final nine years ago.
Since then he has only reached one final - when he lost to Novak Djokovic in 2015 - and says claiming the US Open trophy again this year is a "bigger priority".
And the second seed started his quest by despatching Nishioka with his usual effortless grace in what was largely a straightforward win.
Federer broke his opponent's serve in the first game of the match, then again in the fifth, while allowing Nishioka to win just seven receiving points in the first set.
The onslaught continued in the second set as Federer raced 3-0 ahead, before he clinically turned three break points for Nishioka into a hold with the help of three aces.
Understandably Nishioka's spirit diminished further as the Australian Open champion, enjoying himself with a full repertoire of shots, continued to dominate.
After wrapping up the second set, Federer continued to be aggressive in the third and again grabbed a double break to lead 4-0.
Sloppiness surprisingly crept into his game as Nishioka saved a match point at 5-2, before Federer missed an overhead volley at deuce which was wrongly called in and not challenged by his opponent.
Federer conceded the game amid confusion among the crowd on Ashe, and then was broken for the first time in the following game when Nishioka converted his sixth break point of the set.
But he regained his composure to wrap up victory and continue his flawless first-round record at Flushing Meadows.