PARIS — Jelena Ostapenko became only the sixth female Grand Slam champion to lose in the opening round of their title defense Sunday when she lost to Kateryna Kozlova at the French Open.

The world No. 5 never looked at ease on the Roland Garros main show court, slumping to a 7-5, 6-3 defeat to a Ukrainian opponent who had won both the pair's previous meetings.

Not since Anastasia Myskina lost in the opening round of the 2005 tournament has the French Open lost its women's champion so early.

By losing, Ostapenko joins a ignominious group including, as well as Myskina, Steffi Graf, Jennifer Capriati, Svetlana Kuznetsova and Angelique Kerber who all lost as Grand Slam champions on the first run of their defenses.

Kozlova, competing with a large, weeping blister on her heel which caused her to take a medical break at the end of the first set, was well worth the victory, playing with power and composure, in contrast to the flustered champion.

Ostapenko's eyes searched the coach's box at every opportunity, but could find no answers as she checked out early.

It might appear lower-ranked players are becoming something of an Achilles' heel to the Latvian — already this year she had lost to two players outside the world's top 50. Kozlova, ranked 66, makes it an unhappy hat trick for the 20-year-old.

Fourth seed Grigor Dimitrov reached the second round, even if he wasn't exactly sure who he was facing, while Venus Williams was defeated and Australian firebrand Nick Kyrgios limped out.

Dimitrov had been drawn to face experienced Viktor Troicki in the tournament opener on Philippe Chatrier Court.

However, just before he was due to go on court, Troicki withdrew with a back injury, allowing Egyptian world No. 182 Mohamed Safwat to make his Grand Slam debut.

In the process, he became the first Egyptian since Tamer El Sawy at the 1996 US Open to feature in a major.

"I was warming up and my coach said, 'hey look' and we saw up on the board that I was playing a different opponent," said 27-year-old Dimitrov, a former Wimbledon semifinalist, after his 6-1, 6-4, 7-6 (7/1) win.

"I didn't expect that."

Safwat, 27, had lost in the final round of qualifying in what was his eighth futile attempt to make the main draw of the majors.

But Safwat, one of eight lucky losers in the men's draw, then overcame blisters on his right hand to put up a solid challenge in the third set before Dimitrov raced through the tiebreaker.

"I only heard I was playing an hour before the match," said Safwat.

"I dealt with it as best I could. I had never set foot on that court before."

Seven-time major winner Venus Williams suffered back-to-back opening round exits at the Slams for the first time in her 21-year career.

The ninth-seeded, 37-year-old American slumped to a 6-4, 7-5 defeat to China's world 91 Wang Qiang, a player she knocked out in Paris last year.

Williams, playing Roland Garros for the 21st time, was in no mood for lengthy explanations after her loss.

"Nobody plans for this," she said.

Kyrgios was forced to withdraw after failing to recover from an elbow injury, saying a potential five sets on clay was "too risky".

The 23-year-old was seeded 21 and was due to play compatriot Bernard Tomic in the first round.

The enigmatic Kyrgios has not played a singles match since a quarterfinal loss to Ivo Karlovic at the US Clay Court Championships in April.

"Having consulted with my team and medical experts it is deemed too risky for me to step out and potentially play five sets on clay, especially as I have not played a singles match in nearly two months," Kyrgios wrote on Twitter.

Kyrgios's withdrawal meant that eight places in the first round were opened up to lucky losers.

Defending champion Rafael Nadal, who starts his campaign for an 11th Roland Garros title Monday, will also face a lucky loser.

Italy's world 130 Simone Bolelli moved into the draw after Ukraine's Alexandr Dolgopolov pulled out with a wrist injury.

Women's fourth seed Elina Svitolina, a quarterfinalist in Paris in 2015 and 2017, overcame a first set 1-5 deficit to see off Australia's Ajla Tomljanovic 7-5, 6-3.

Svitolina next faces Slovakia's Viktoria Kuzmova who put out 2010 champion Francesca Schiavone, the 37-year-old Italian who made it through qualifying, 7-6 (7/2), 7-6 (7/2).

Other early winners on Sunday included Estonian 25th seed Anett Kontaveit who downed Madison Brengle of the United States 6-1, 4-6, 6-2.

Kontaveit defeated Australian Open champion Caroline Wozniacki on her way to the semifinals in Rome last week.

She was also a semifinalist on clay in Stuttgart while also beating Venus Williams in Madrid.

US Open champion Sloane Stephens, the 10th seed, needed just 49 minutes to breeze past Arantxa Rus 6-2, 6-0.

Pavlyuchenkova wins

Russian Anastasia Pavlyuchenkova claimed her 12th WTA Tour title Saturday by beating Slovakia’s Dominika Cibulkova in a grueling final in Strasbourg.

Pavlyuchenkova, the world number 31, saved two match points in the 10th game of the deciding set before winning 6-7 (5/7), 7-6 (7/3), 7-6 (8/6) after over three and a half hours of play.

It was the 26-year-old’s first final since winning in Hong Kong last October, but she managed to outlast former Australian Open runner-up Cibulkova. — Agencies