Serena's winning return

Serena Williams made a triumphant return to the US Open on Monday, launching her bid for a record-equalling 24th Grand Slam victory with a straight-sets win.

Williams, who counts six US Open titles among her 23 Grand Slams, can match Margaret Court's all-time record of 24 majors with a title.

She missed last year's edition due to the birth of a child 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.

World number two Carolinse Wozniacki also advanced, dispatching former champion Samantha Stosur 6-3, 6-2. Venus, a seven-time Slam winner, outlasted another former champion, Svetlana Kuznetsova, 6-3, 5-7, 6-3.

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.

Defending US Open champion Rafael Nadal sent close friend David Ferrer into Grand Slam retirement when his veteran compatriot was forced to quit their match with injury, but former winners Andy Murray and Stan Wawrinka made successful returns.

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."

Nadal's potential semifinal opponent, 2009 champion Juan Martin del Potro, reached the second round with a 6-0, 6-3, 6-4 win over Donald Young.

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, playing just his fifth tournament of the year after undergoing surgery in January, last featured in a major at Wimbledon in 2017.

Greek 15th seed Stefanos Tsitsipas saw off 36-year-old Tommy Robredo of Spain 6-3, 7-6 (7/1), 6-4.