JOIN USDefending US Open champion Rafael Nadal sent close friend David Ferrer into Grand Slam retirement on Monday when his veteran compatriot was forced to quit their first round match with injury, but former winners Andy Murray and Stan Wawrinka made successful returns to New York.
Ferrer, a former world number three but now standing at a lowly 148, called it quits on a hot and humid night on Arthur Ashe Stadium despite leading 4-3 with a break in the second set after twice receiving treatment on a left leg injury.
Top seed Nadal had taken the opener 6-3.
"This is my last Grand Slam," said Ferrer who was runner-up to Nadal in the 2013 French Open final.
"I have great memories of this tournament and I am just sorry that I couldn't finish it tonight." Ferrer, 36, will play his last tournament on home ground in Madrid next year.
Nadal, chasing his 18th Grand Slam title, will face Canada's Vasek Pospisil for a place in the last 32.
Nadal's potential semifinal opponent, Argentine third seed and 2009 champion Juan Martin del Potro, also reached the second round with a 6-0, 6-3, 6-4 win over American qualifier Donald Young.
Del Potro next faces Denis Kudla of the United States who won his first match in five years at the tournament when he downed Matteo Berrettini of Italy 6-4, 7-5, 6-2. Former world number one Murray marked his first Grand Slam tournament in 14 months with a 6-7 (5/7), 6-3, 7-5, 6-3 win over Australia's James Duckworth.
Murray, the 2012 champion and playing just his fifth tournament of the year after undergoing hip surgery in January, last featured in a major at Wimbledon in 2017.
Like Murray, former champion Wawrinka also sat out the 2017 US Open -- in his case because of two knee surgeries.
But he showed no sign of rustiness on Monday, defeating eighth-seeded Grigor Dimitrov of Bulgaria for the second successive Grand Slam.
Wawrinka, the 2016 champion, swept to a 6-3, 6-2, 7-5 victory on Arthur Ashe Stadium to repeat his opening round triumph over Dimitrov at Wimbledon.
Serena wins
Serena Williams made a winning return to the tournament on Monday, launching her bid for a record-equalling 24th Grand Slam victory with a straight-set win as top-seeded Simona Halep made dubious history with a first-round exit.
Serena, who counts six US Open titles among her 23 Grand Slams, can match Margaret Court's all-time record of 24 majors with another title at Flushing Meadows.
She missed last year's edition as she gave birth to daughter Olympia on September 1, but showed every indication she's ready to make up for lost time in a 6-4, 6-0 victory over Poland's Magda Linette.
Venus Williams, a seven-time Slam winner, outlasted another former champion, Svetlana Kuznetsova, 6-3, 5-7, 6-3.
Neither Williams sister was willing to look too far ahead, Venus noting that Halep's ouster was proof of just how dangerous any opponent can be.
Defending champion Sloane Stephens encountered late resistance but held on for a 6-1, 7-5 victory over Russian Evgeniya Rodina.
Elsewhere on the opening day, seventh-seeded Spaniard Garbine Muguruza advanced with a 6-3, 6-0 victory over China's Zhang Shuai.
Two-time Grand Slam winner Victoria Azarenka, a former world number one now ranked 80th in the world, defeated Viktoria Kuzmova 6-3, 7-5 to st up a meeting with Australian Daria Gavrilova, who steamrolled Sara Sorribes 6-0, 6-0.