Nadal won the first set but trailed 3-4 in the second when Ferrer had to stop because of injury.
Women's first round: No. 2 Caroline Wozniacki beat Samantha Stosur 6-3, 6-2; No. 5 Petra Kvitova beat Yanina Wickmayer 6-1, 6-4; No. 10 Jelena Ostapenko beat Andrea Petkovic 6-4, 4-6, 7-5; No. 20 Naomi Osaka beat Laura Siegemund 6-3, 6-2; Kirsten Flipkens beat No. 24 CoCo Vandeweghe 6-3, 7-6 (3). "This is the last grand slam of my career and I am so sorry because I can't finish the match".
"I'm improving tournament after tournament, match after match".
Former World No. 1 Murray marked his first Grand Slam tournament in 14 months with a 6-7 (5), 6-3, 7-5, 6-3 win over Australia's James Duckworth. Andy Murray, who won the first of his three Slam trophies in 2012 at Flushing Meadows, is also on Ashe, taking on No. 31 seed Fernando Verdasco.
The item had more than 4 million views by Monday evening, when Williams beat Magda Linette 6-4, 6-0 in the first round of the U.S. Open.
Simona Halep crashed out in the first round, becoming the first No. 1 seed in the Open era to do so.
But Anderson, defeated in the Wimbledon final last month by Novak Djokovic, recovered to win 7-6, 5-7, 4-6, 6-3, 6-4.
"That's life. Yeah, he deserved a better finish on a grand slam".
"But I started to get into the return games, stood back a little more and that gave me more time to get in the rallies and find my range with my ground strokes".
"My experience is I don't see people get insane and involved in the match when the ball, all it goes (is) two or three times over the net every time", he added."I see the people go insane and enjoy and feel the passion for the sport when you have rallies of 15, 20 balls" that's my feeling.
As for the players who have to cope with the sweltering conditions, it is all part of the brutal test that is the fourth and final Grand Slam of the year.
"I have really good memories here at the US Open", Ferrer said.
Williams' path may have been eased by Kaia Kanepi's stunning upset of world number one Halep, who became the first top-seeded woman to lose in the first round of the US Open.
Shapovalov was leading 7-5, 5-7, 4-1 when Auger-Aliassime retired.
Like Murray, former champion Stan Wawrinka also sat out the 2017 US Open - in his case because of two knee surgeries.
Auger-Aliassime, making his Slam debut after coming through qualifying, had needed a medical timeout for an irregular hearbeat in the third set.
Wawrinka, the former world No 3, now down at 101, shrugged off having to take a medical time-out early in the third set. He was seeded 12th and with the fierce competition available in the men's event everyone was looking to either Federer or Nadal, the top two ranked players to take the title.