Serena Williams delayed her farewell to tennis on an electrifying opening night at the US Open on Monday as the sporting icon battled to victory in front of a star-studded crowd.

The 23-time Grand Slam winner - who earlier this month signalled she plans to retire from tennis after the tournament - drew on all of her experience to down lowly ranked Montenegrin opponent Danka Kovinic 6-3, 6-3.

A galaxy of celebrities ranging from Hollywood stars, fashion icons and former presidents were out in force at Flushing Meadows' Arthur Ashe Stadium to watch could have been Williams final appearance in a Grand Slam singles match.

But the 40-year-old ensured that her legions of fans will have at least one more chance to savour her talents as she dug out victory despite an error-strewn display.

"I feel so comfortable on this court and in front of everyone here," a jubilant Williams said after her victory.

"The crowd was crazy - they really helped pull me through. I was really pumped," added Williams, who won the first of her Grand Slam titles in the same arena in 1999 as a 17-year-old prodigy.

Williams admitted that deciding to walk away from the sport after 27 years as a professional was "such a hard decision."

"I think when you are passionate about something it is always hard to walk away," she said. "I have been trying to decide what to do. I love this game.

"But I was just like 'Alright, I think now's the time'. I have a family, there's other chapters in life. I call it evolution."

Williams later refused to be definitive about her retirement however when asked if the US Open would be her last tournament, teasing the possibility that she may yet play on.

"I've been pretty vague about it, right?" she said. "I'm going to stay vague because you never know."

A sell-out crowd of 23 500 had roared its appreciation for Williams as she strode into the arena wearing a striking sparkling bodice and black skirt comprised of six layers -- one for every US Open title she has won.

The roll-call of A-listers on hand for the occasion included former US President Bill Clinton, Vogue editor Anna Wintour, former heavyweight champion Mike Tyson, tennis legend and Hollywood stars such as Hugh Jackman and Queen Latifah.

Williams acknowledged that leaving the spotlight - whenever that is - would be a wrench.

"The more tournaments I play, I feel like the more I can belong out there," she said. "That's a tough feeling to have, to leave knowing the more you do it, the more you can shine."

Tsitsipas stunned

In other women's draw action on Monday, former world number one Simona Halep, seeded seventh, was the biggest casualty in the first round, crashing out 6-2, 0-6, 6-4 to Ukrainian qualifier Daria Snigur.

But there were no such problems for US teenager and 12th seed Coco Gauff, who cruised past France's Leolia Jeanjean 6-2, 6-3.

Meanwhile the men's draw got under way with a stunning upset for Greek fourth seed Stefanos Tsitsipas, who was bundled out by Colombian qualifier Daniel Elahi Galan 6-0, 6-1, 3-6, 7-5.

Earlier, Russia's defending champion Daniil Medvedev routed Stefan Koslov of the United States in the top half of the draw.

The Russian comfortably dispatched world No 111 Kozlov 6-2, 6-4, 6-0 in 2hrs 1min.

Medvedev, bidding to become the first man to defend the US crown since Roger Federer retained the title in 2008, faces France's Arthur Rinderknech in the second round.

Britain's Andy Murray, another veteran well into the twilight of his career, marked the 10th anniversary of his maiden Grand Slam win with a straight sets defeat of Argentinian 24th seed Francisco Cerundolo.

The 35-year-old Scot showed no signs of recent cramping problems in a 7-5, 6-3, 6-3 win, but admitted afterwards: "It felt like five sets."

It was Murray's first straight sets win at a Grand Slam event since 2017.

Elsewhere on Monday, Wu Yibing claimed a piece of history in the men's draw, becoming the first man from China to win a Grand Slam singles match since 1959.

The qualifier upset Georgia's 31st seed Nikoloz Basilashvili 6-3, 6-4, 6-0.

But there was agony for China's other player in the men's draw, Zhang Zhizhen who squandered seven match points in a 3-6, 6-7 (4/7), 7-6 (11/9), 6-1, 6-4 defeat to Tim van Rijthoven of the Netherlands.

Spain's Rafael Nadal, chasing a fifth US Open crown and 23rd Grand Slam title overall, begins his campaign on Tuesday against Australia's Rinky Hijikata.

US Open results on Monday (x denotes seed; players representing Russia and Belarus are banned from competing under the name or flag of their countries):

Men

First round

Daniil Medvedev (x1) bt Stefan Kozlov (USA) 6-2, 6-4, 6-0

Arthur Rinderknech (FRA) bt Quentin Halys (FRA) 4-6, 7-6 (7/4), 6-3, 6-2

Nuno Borges (POR) bt Ben Shelton (USA) 7-6 (8/6), 3-6, 7-6 (7/5), 6-7 (8/10), 6-3

Wu Yibing (CHN) bt Nikoloz Basilashvili (GEO x31) 6-3, 6-4, 6-0

Nick Kyrgios (AUS x23) bt Thanasi Kokkinakis (AUS) 6-3, 6-4, 7-6 (7/4)

Benjamin Bonzi (FRA) bt Ugo Humbert (FRA) 7-6 (7/1), 6-1, 5-7, 3-6, 6-2

Alejandro Tabilo (CHI) bt Kamil Majchrzak (POL) 6-1, 6-4, 6-7 (3/7), 6-1

JJ Wolf (USA) bt Roberto Bautista Agut (ESP x16) 6-4, 6-4, 6-4

Pablo Carreno Busta (ESP x12) bt Dominic Thiem (AUT) 7-5, 6-1, 5-7, 6-3

Alexander Bublik (KAZ) bt Hugo Gaston (FRA) 6-4, 6-4, 6-4

Christian Garín (CHI) bt Jirí Lehecka (CZE) 3-6, 7-6 (7/3), 7-5, 6-1

Alex De Minaur (AUS x18) bt Filip Krajinovic (SRB) 7-5, 6-2, 6-3

Karen Khachanov (x27) bt Denis Kudla (USA) 3-6, 6-1, 6-2, 6-2

Thiago Monteiro (BRA) bt Alex Molcan (SVK) 6-4, 4-6, 6-4, 6-1

Jack Draper (GBR) bt Emil Ruusuvuori (FIN) 6-4, 6-3, 6-3

Felix Auger-Aliassime (CAN x6) bt Alexander Ritschard (SUI) 6-3, 6-4, 3-6, 6-3

Daniel Elahi Galan (COL) bt Stefanos Tsitsipas (GRE x4) 6-0, 6-1, 3-6, 7-5

Jordan Thompson (AUS) bt Lorenzo Sonego (ITA) 2-6, 1-6, 6-2, 6-4, 6-4

Alejandro Davidovich Fokina (ESP) bt Yoshihito Nishioka (JPN) 6-3, 7-5, 6-3

Marton Fucsovics (HUN) bt Maxime Cressy (USA x30) 6-7 (4/7), 7-5, 5-1 - retired

Andy Murray (GBR) bt Francisco Cerundolo (ARG x24) 7-5, 6-3, 6-3

Emilio Nava (USA) bt John Millman (AUS) 7-6 (9/7), 4-6, 7-6 (7/4), 1-6, 6-1

Hugo Grenier (FRA) bt Tomas Etcheverry (ARG) 4-6, 6-2, 6-3, 6-4

Matteo Berrettini (ITA x13) bt Nicolas Jarry (CHI) 6-2, 6-3, 6-3

Brandon Holt (USA) bt Taylor Fritz (USA x10) 6-7 (3/7), 7-6 (7/1), 6-3, 6-4

Pedro Cachín (ARG) bt Aljaz Bedene (SLO) 6-4, 6-3, 5-7, 1-6, 7-6 (10/6)

Corentin Moutet (FRA) bt Stan Wawrinka (SUI) 6-4, 7-6 (9/7) -- retired

Botic van de Zandschulp (NED x21) bt Tomas Machac (CZE) 3-6, 7-6 (7/3), 6-1, 3-6, 7-5

Tommy Paul (USA x29) bt Bernabe Zapata Miralles (ESP) 4-6, 6-3, 2-6, 6-0, 7-5

Sebastian Korda (USA) bt Facundo Bagnis (ARG) 5-7, 7-6 (7/3), 7-5, 6-1

Tim Van Rijthoven (NED) bt Zhang Zhizhen (CHN) 3-6, 6-7 (4/7), 7-6 (11/9), 6-1, 6-4

Casper Ruud (NOR x5) bt Kyle Edmund (GBR) 6-3, 7-5, 6-2

Women

First round

Daria Snigur (UKR) bt Simona Halep (ROM x7) 6-2, 0-6, 6-4

Rebecca Marino (CAN) bt Magdalena Frech (POL) 6-2, 6-3

Anna Karolina Schmiedlova (SVK) bt Nadia Podoroska (ARG) 6-3, 6-2

Zhang Shuai (CHN) bt Jil Teichmann (SUI x30) 6-4, 6-2

Madison Keys (USA x20) bt Dayana Yastremska (UKR) 7-6 (7/3), 6-3

Camila Giorgi (ITA) bt Anna Bondar (HUN) 4-6, 6-3, 6-1

Gabriela Ruse (ROM) bt Daria Saville (AUS) 3-6, 6-2, 6-4

Coco Gauff (USA x12) bt Leolia Jeanjean (FRA) 6-2, 6-3

Beatriz Haddad Maia (BRA x15) bt Ana Konjuh (CRO) 6-0, 6-0

Bianca Andreescu (CAN) bt Harmony Tan (FRA) 6-0, 3-6, 6-1

Anna Kalinskaya bt Rebecca Peterson (SWE) 6-4, 6-3

Caroline Garcia (FRA x17) bt Kamilla Rakhimova 6-2, 6-4

Alison Riske (USA x29) bt Eleana Yu (USA) 6-2, 6-4

Maria Camila Osorio (COL) bt Ann Li (USA) 1-6, 6-3, 6-1

Wang Xiyu (CHN) bt Diane Parry (FRA) 5-7, 6-3, 6-3

Maria Sakkari (GRE x3) bt Tatjana Maria (GER) 6-4, 3-6, 6-0

Ons Jabeur (TUN x5) bt Madison Brengle (USA) 7-5, 6-2

Elizabeth Mandlik (USA) bt Tamara Zidansek (SLO) 5-7, 7-6 (7/3), 6-4

Viktoria Kuzmova (SVK) bt Sara Sorribes Tormo (ESP) 6-3, 6-4

Shelby Rogers (USA x31) bt Arantxa Rus (NED) 3-6, 6-3, 6-4

Veronika Kudermetova (x18) bt Donna Vekic (CRO) 7-5, 6-3

Maryna Zanevska (BEL) bt Coco Vandeweghe (USA) 6-1, 7-5

Dalma Galfi (HUN) bt Nuria Parrizas Diaz (ESP) 6-4, 6-3

Harriet Dart (GBR) bt Daria Kasatkina (x10) 7-6 (10/8), 1-6, 6-3

Leylah Fernandez (CAN x14) bt Océane Dodin (FRA) 6-3, 6-4

Liudmila Samsonova bt Sara Bejlek (CZE) 6-3, 6-1

Aleksandra Krunic (SRB) bt Elina Avanesyan 6-4, 6-4

Barbora Krejcikova (CZE x23) bt Fernanda Contreras Gomez (MEX) 6-0, 6-4

Evgeniya Rodina bt Martina Trevisan (ITA x27) 7-5, 6-1

Ajla Tomljanovic (AUS) bt Karolína Muchova (CZE) 6-3, 7-6 (7/5)

Serena Williams (USA) bt Danka Kovinic (MNE) 6-3, 6-3

Anett Kontaveit (EST x2) bt Jaqueline Cristian (ROM) 6-3, 6-0