July 26 (UPI) -- Men's No. 1 Novak Djokovic and women's No. 2 Naomi Osaka breezed into the third round, while Aryna Sabalenka and Iga Swiatek suffered shock upsets in the 2020 Summer Games singles tennis tournaments Monday in Tokyo.
Djokovic dispatched of Germany's Jan-Lennard Struff in straight sets at Ariake Tennis Park. The Serbian battles Spain's Alejandro Davidovich Fokina on Wednesday for a chance to play in the men's quarterfinals.
Djokovic fired 14 aces, converted three of three break points and totaled just four unforced error in the win. Davidovich Fokina (No. 34) beat No. 44 John Millman of Australia to advance to the Djokovic matchup.
Osaka, the top-ranked player left in the women's tournament due to No. 1 Ash Barty's first-round upset, displayed dominance Monday. She needed just 65 minutes to dispatch of Switzerland's Viktorija Golubic.
Osaka will represent Japan against No. 42 Marketa Vondrousova of the Czech Republic in the third round. She fired three aces, converted three of five break points and totaled just 11 unforced errors in Monday's 6-3, 6-1 win.
No. 6 Elina Svitolina of the Ukraine, No. 7 Karolina Pliskova of the Czech Republic, No. 9 Garbine Muguruza of Spain, No. 11 Barbora Krejcikova of the Czech Republic and No. 12 Belinda Bencic of Switzerland were among the other top-ranked women to advance.
No. 18 Anastasia Pavlyuchenkova of the Russian Olympic Committee, No. 19 Maria Sakkari of Greece and No. 20 Elena Rybakina of Kazakhstan also won their second-round matches.
Sabalenka (No. 3) became the second Top 3 player to lose through the first two rounds when she fell to No. 50 Donna Vekic of Croatia in three sets Monday in Tokyo. The Belarusian totaled 44 forced errors and 34 unforced errors and converted just two of 12 break points in the loss.
Vekic faces Rybakina in her next match for a shot at the quarterfinals.
Swiatek, of Poland, lost to Spain's Paula Badosa in her second-round match. The No. 6 player in the WTA rankings converted two of five break points and registered 32 unforced errors in the loss.
Alison Uytvanck of Belgium also staged an upset in her second-round singles match. She bounced No. 13 Petra Kvitova of the Czech Republic in three sets to reach the third round.
Bencic battles Krejcikova in a matchup of Top 10 players in the next round of the Summer Games women's singles tournament.
Third-round play in the men's and women's tournaments airs at 10 p.m. EDT Monday on NBC's Olympic Channel.