Sixth seed Madison Keys was sent tumbling out of the US Open, losing in straight sets to lowly ranked Mexican player Renata Zarazua.

Reigning Australian Open champion Keys bowed out after an attritional battle with Zarazua, who prevailed 6-7 (10/12), 7-6 (7/3), 7-5.

Zarazua, ranked 82 in the world, took advantage of Keys’ problems with her service game to claim an impressive win.

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Keys gave up 14 double faults and was broken six times as Zarazua battled into a second-round meeting with France’s Diane Parry.

Keys’ defeat comes after a solid season in Grand Slams following her maiden victory at the Australian Open in January. She reached the quarter-finals at the French Open before progressing to the third round at Wimbledon.

Madison Keys, of the United States, reacts in the first set against Renata Zarazua, of Mexico, during the first round of the US Open tennis championships, Monday, Aug. 25, 2025, in New York. (AP Photo/Seth Wenig)Source: AP

Meanwhile, Carlos Alcaraz opens his bid for a sixth Grand Slam title at the US Open as Venus Williams prepares to make a record-extending 25th appearance at the tennis showpiece.

The second full day of action at the Billie Jean King National Tennis Center at Flushing Meadows will see all eyes on the Arthur Ashe Stadium court as Alcaraz and Williams headline the night session.

Spanish star Alcaraz is chasing a second US Open title following his maiden Grand Slam victory at the tournament in 2022, and faces big-serving American Reilly Opelka in the first round.

The 22-year-old second seed is on course for another blockbuster showdown with Jannik Sinner in New York, after already meeting the Italian twice in Grand Slam finals this season.

NEW YORK, NEW YORK – AUGUST 23: Carlos Alcaraz of Spain in good spirits during a practice session ahead of the US Open at USTA Billie Jean King National Tennis Center on August 23, 2025 in New York City. (Photo by Clive Brunskill/Getty Images)Source: Getty Images

US tennis icon Williams, meanwhile, will kick off what could well turn out to be her final US Open campaign when she takes on Czech 11th seed Karolina Muchova in the first round.

The 45-year-old, who is ranked 602nd in the world, was handed a wildcard into the first round of the women’s singles draw in New York after returning to tennis in July following a 16-month absence from the sport.

Racquet demolished! BRUTAL Medvedev loss | 00:31

– Kvitova farewell –

This year’s appearance comes some 28 years after she first graced the US Open as a 17-year-old in 1997, going on a fairytale run to the final, where she was defeated by Martina Hingis.

“It does not get old; it just gets more exciting,” Williams said on Saturday of her excitement about playing in the open.

Williams’ participation also falls on the 75th anniversary of African-American tennis trailblazer Althea Gibson’s first appearance at the US national championships in 1950. A ceremony marking that milestone will take place on Arthur Ashe before Williams’ match later Monday.

NEW YORK, NEW YORK – AUGUST 20: Venus Williams Trains prior to the start of the US Open at USTA Billie Jean King National Tennis Center on August 20, 2025 in New York City. (Photo by Al Bello/Getty Images)Source: Getty Images

“I think the most important part is that we are celebrating it and recognising it, because Althea accomplished so much, and a lot of it has not been given the credit it deserves and the attention and the praise,” Williams said.

“I think that’s the most important part to me, just shining light on it and seeing, just acknowledging that.”

NEW YORK, NEW YORK – AUGUST 23: Venus Williams fields questions during a press conference at USTA Billie Jean King National Tennis Center on August 23, 2025 in New York City. Maddie Meyer/Getty Images/AFP (Photo by Maddie Meyer / GETTY IMAGES NORTH AMERICA / Getty Images via AFP)Source: AFP

Elsewhere, early action saw two-time Wimbledon champion Petra Kvitova formally bring the curtain down on her career after a 6-1, 6-0 defeat to France’s Diane Parry.

The 35-year-old Czech had already announced her intention to retire after the US Open, but was nonetheless overcome with emotion as she bade farewell to the sport, breaking down in tears as she addressed fans after her game.

“I hoped I would put on a better show today,” Kvitova said after her loss. “It was tough to know it could be my last match, and emotionally it was very tough as well.”

In other early games, Czech veteran Barbora Krejcikova bundled out rising Canadian star Victoria Mboko, defeating the teenager 6-3, 6-2.

Belgian 19th seed Elise Mertens ousted wildcard entrant Alyssa Ahn 6-1, 6-0, while Ukrainian 30th seed Dayana Yastremska exited in a 6-7 (5/7), 7-6 (7/5), 6-4 loss to Russian player Anastasia Pavlyuchenkova.

In the men’s draw, meanwhile, qualifier Coleman Wong scored a notable first, becoming the first player from Hong Kong to record a victory in a Grand Slam singles event in the Open era with a 6-4, 5-7, 7-6 (7/4) defeat of US player Aleksandar Kovacevic.

Results from US Open tennis tournament at Billie Jean King Tennis Center in New York on Monday (x denotes seed):

Men 1st rd

Zizou Bergs (BEL) bt Tseng Chun-Hsin (TPE) 6-3, 6-4, 6-3

Adam Walton (AUS) bt Ugo Humbert (FRA x22) 6-4, 7-6 (7/4), 5-7, 6-1

Coleman Wong (HKG) bt Aleksandar Kovacevic (USA) 6-4, 7-5, 7-6 (7/4)

Cameron Norrie (GBR) bt Sebastian Korda (USA) 7-5, 6-4, 0-0 abandon

Martin Damm Jr. (USA) bt Darwin Blanch (USA) 6-3, 6-4, 6-4

Joao Fonseca (BRA) bt Miomir Kecmanovic (SRB) 7-6 (7/3), 7-6 (7/5), 6-3

Lloyd Harris (RSA) bt Sebastian Baez (ARG) 6-3, 7-5, 6-4

Women 1st rd

Elise Mertens (BEL x19) bt Alyssa Ahn (USA) 6-1, 6-0

Elena Rybakina (KAZ x9) bt Julieta Pareja (USA) 6-3, 6-0

Iva Jovic (USA) bt Aliaksandra Sasnovich (BLR) 7-6 (8/6), 6-3

Anastasia Pavlyuchenkova (RUS) bt Dayana Yastremska (UKR x30) 6-7 (5/7), 7-6 (7/5), 6-4

Liudmila Samsonova (RUS x17) bt Yuan Yue (CHN) 2-6, 6-4, 6-4

Priscilla Hon (AUS) bt Leolia Jeanjean (FRA) 6-3, 7-5

Barbora Krejcikova (CZE) bt Victoria Mboko (CAN x22) 6-3, 6-2

Taylor Townsend (USA) bt Antonia Ruzic (CRO) 6-4, 6-4

Renata Zarazua (MEX) bt Madison Keys (USA x6) 6-7 (10/12), 7-6 (7/3), 7-5

Diane Parry (FRA) bt Petra Kvitova (CZE) 6-1, 6-0

Yulia Putintseva (KAZ) bt Elisabetta Cocciaretto (ITA) 6-4, 7-6 (7/4)