World No 1 Naomi Osaka’s hopes of winning a third successive Grand Slam ended Saturday when she was knocked out of the French Open in the third round by doubles world No 1 Katerina Siniakova of the Czech Republic.

Japanese top seed Osaka, the reigning US and Australian Open champion, crashed to a 6-4, 6-2 defeat to the 42nd-ranked Czech.

In another match, Serena Williams’s bid to win a record-equalling 24th Grand Slam title was thwarted again when she was knocked out of the French Open 6-2, 7-5 by US compatriot Sofia Kenin in the third round.

It was 37-year-old Serena’s earliest exit at the Slams since a third-round loss to Alize Cornet at Wimbledon in 2014.

Kenin, the 20-year-old world number 35, will face eighth seed Ashleigh Barty of Australia for a place in the quarter-finals.

Three-time Roland Garros champion Williams was attempting to equal Margaret Court’s record of 24 majors.

“There’s a lot of emotions now,” said Kenin who wasn’t even born when Williams made her Paris debut in 1998.

“Serena is such a great champion and I have all the respect for her. I had to fight for every point.”

Williams, who has still to add to her majors collection since she returned to the tour after giving birth to her daughter, fired 30 winners and 34 unforced errors.

Osaka’s errors

Osaka was undone by a shocking 38 unforced errors as she finally ran out of luck in Paris having had to come back from a set down in her first two matches.

“It’s amazing, I can’t believe it, I am so happy now,” said Siniakova, who was the women’s doubles champion in Paris in 2018 alongside Barbora Krejcikova.

“I played my best tennis and I hope it continues.”

Osaka dropped the first set for the third successive match at the tournament, squandering seven break points in all. Siniakova made her pay, breaking for 5-4 and taking the opener when Osaka sent back her 16th unforced error of the set.

The Czech, who is the world’s No 1 doubles player, kept up the pressure on the misfiring top seed, breaking for a 3-2 lead in the second set.

Siniakova backed it up with another break for 5-2 off Osaka’s third double fault of the match.

Victory was hers on Court Suzanne Lenglen when Osaka unleashed another misguided forehand.

The Czech goes on to face either Madison Keys of the United States or Russian qualifier Anna Blinkova for a place in the quarter-finals in what will be her first appearance in the last 16 of the majors.

Despite being seeded top for the first time at a Slam, the 21-year-old Osaka had never looked convincing in Paris.

She was two points away from defeat in the first round against Anna Karolina Schmiedlova and came back from a set and break down to see off Victoria Azarenka in round two.

Her defeat also means that only four of the top 10 seeds in the women’s singles are left in the tournament.

Earlier, reigning champion Simona Halep cruised into the Roland Garros fourth round with a 6-2, 6-1 thrashing of Ukrainian 27th seed Lesia Tsurenko.

The Romanian third seed broke serve eight times in a totally one-sided contest that lasted just 55 minutes to set up a last-16 tie with either Olympic champion Monica Puig or Polish teenager Iga Swiatek.

French Open women’s last 16 line-up (x denotes seeded player):

Katerina Siniakova (CZE) v Madison Keys (USA x14)

Sofia Kenin (USA) v Ashleigh Barty (AUS x8)

Simona Halep (ROM x3) v Iga Swiatek (POL)

Amanda Anisimova (USA) v Aliona Bolsova (ESP)

Sloane Stephens (USA x7) v Garbine Muguruza (ESP x19)

Donna Vekic (CRO x23) v Johanna Konta (GBR x26)

Marketa Vondrousova (CZE) v Anastasija Sevastova (LAT x12)

Kaia Kanepi (EST) v Petra Martic (CRO x31)

With AFP inputs