June 1 (UPI) -- Americans Serena Williams and Sofia Kenin defeated their first round foes while Roger Federer won his first Grand Slam match in 16 months to advance to the second round at the 2021 French Open.
Federer bounced Denis Istomin 6-2, 6-4, 6-3 in one hour, 33 minutes Monday on Court Philippe-Chatrier at Roland Garros in Paris. The straight sets victory was Federer's first Grand Slam win since he defeated Tennys Sandgren on Jan. 27 at the 2020 Australian Open.
Federer -- ranked No. 8 -- fired eight aces, 48 winners and did not log a double fault in the victory. Istomin totaled three aces, four double faults and did not win a break point in the loss. Federer takes on Marin Cilic in the second round Wednesday in Paris.
"The type of the opponent allowed me to have many different ways to win points," Federer told reporters. "I knew if i came to the net that was an option. Hitting the drop shot was always an option and taking the ball early was an option."
No. 2 Daniil Medvedev was the highest-ranked player to advance on the men's singles circuit. He beat Alexander Bublik in straight sets to advance to the second round.
Kenin, the No. 5 player in the world, was the highest-ranked player to advance Monday on the women's singles circuit. She beat Jelena Ostapenko 6-4, 4-6, 6-3 in two hours and five minutes.
The 2020 French Open runner up trailed Ostapenko 3-0 in aces and logged six double faults, but converted nine of 10 break points and won 53 of 97 receiving points. Ostapenko tallied just four double faults and won 14 of 18 net point opportunities in the loss. She also fired 32 winners, compared to Kenin's 23.
Kenin faces fellow American Hailey Baptiste in the second round Wednesday at Roland Garros.
Williams, a three-time French Open champion, beat Romanian Irina-Camelia Begu in straight sets to advance to the second round. The No. 8 player in the WTA rankings dispatched of Begu in one hour and 42 minutes.
Williams fired five aces, two double faults and 27 winners in the victory. She totaled 30 unforced errors and won five of eight break point opportunities. The 23-time Grand Slam champion faces Mihaela Buzarnescu in the second round.
"I know what to do," Williams told Tennis Channel. "I've been here a million times. I just have to do it. Because I've been in those positions and those tight shots. That's what I tried to focus on."
Jessica Pegula, Madison Brengle and Baptiste were among the other Americans to advance Monday on the women's singles circuit.
Canadian Bianca Andreescu went down Monday in the biggest upset so far this year at Roland Garros. The 2019 U.S. Open champion, who has dealt with a series of injuries over the last several years, lost to Tamara Zidansek in three sets.
Zidansek fired two aces, two double faults and 41 winners in the three-hour, 20-minute match. Andreescu, ranked No. 7, fired four aces, but totaled eight double faults and 63 unforced errors in the upset loss.
Marta Kostyuk beat No. 13 Garbine Muguruza in another upset Monday on the women's singles circuit. Kostyuk beat Muguruza in straight sets.
No. 9 Iga Swiatek -- the defending champion -- beat Kaja Juvan in straight sets to advance to the second round. No. 11 Belinda Bencic also was among the top women's players to advance Monday out of the singles circuit.
First round men's and women's singles matches air from 5 a.m. to 6 p.m. Tuesday on Tennis Channel. The second round airs from 5 a.m. to 6 p.m. Wednesday and Thursday on Tennis Channel.