(Photo credit: Albert Cesare/The Enquirer / USA TODAY NETWORK via Imagn Images)

Sixth-seeded Madison Keys fought off two match points to rally for a 1-6, 6-3, 7-6 (1) victory over Germany's Eva Lys in second-round action Saturday at the Cincinnati Open in Mason, Ohio.

Keys fell behind 3-0 in the third set. Then, after she could not finish the match on her serve at 5-4, she forced the tiebreaker by staving off those match points. She dominated the tiebreaker and she finished with 12 aces to Lys' none.

'I just kept trying to listen to everyone here cheering me,' Keys said. 'It helped me get back into the match and across the finish line.'

Keys will face Japan's Aoi Ito in third-round play Monday. The 21-year-old from Japan pulled off one of Saturday's six upsets when she knocked out 27th-seeded Anastasia Pavlyuchenkova of Russia 6-1, 4-6, 6-4.

Top-seeded Aryna Sabalenka of Belarus began the defense of her Cincinnati Open title on Saturday night with a 7-5, 6-1 victory over Marketa Vondrousova of the Czech Republic. The world No. 1 converted all three of her break points while denying Vondrousova on all 12 of her break opportunities. Sabalenka will face No. 30 seed Emma Raducanu of Great Britain in the third round as Raducanu took out Serbia's Olga Danilovic 6-3, 6-2.

Fifth-seeded Amanda Amisinova was slated to make her tournament debut Saturday night as well, but she received a walkover against France's Leolia Jeanjean.

Australia's Maya Joint put in the most effort to produce an upset. The 19-year-old needed two hours, 57 minutes to defeat Brazil's Beatriz Haddad Maia 6-4, 4-6, 6-4. Joint, who benefited from 18 double faults by her 18th-seeded opponent, advances to face 12th-seeded Ekaterina Alexandrova. The Russian breezed past New Zealand's Lulu Sun 6-4, 6-2.

Wimbledon champion Iga Swiatek, the No. 3 seed from Poland, took care of Russia's Anastasia Potapova 6-1, 6-4 as Swiatek won 90.3 percent of her first-serve points. Swiatek gets 25th-seeded Marta Kostyuk of Ukraine in the third round as Kostyuk handled Germany's Tatjana Maria 6-0, 6-1.

No. 9 Elena Rybakina of Kazakhstan, No. 19 Elise Mertens of Belgium and No. 28 Anna Kalinskaya of Russia each needed three sets to live up to their seeds. Rybakina rallied to topple Mexico's Renata Zarazua 4-6, 6-0, 7-5, Mertens collected a 3-6, 7-6 (3), 7-5 victory over Clervie Ngounoue and Kalinskaya claimed a 7-6 (4), 4-6, 6-1 verdict over Peyton Stearns.

The other seeded players weren't as fortunate. No. 13 Liudmila Samsonova of Russia suffered a 6-2, 6-4 loss to Taylor Townsend, who cranked out nine aces. No. 14 Diana Shnaider of Russia came up short against China's Yuan Yue by a 6-4, 1-6, 6-3 count. No. 21 Leylah Fernandez of Canada dropped a 6-3, 6-3 decision to Spain's Jessica Bouzas Maneiro and No. 22 Magdalena Frech of Poland was eliminated 7-6 (4), 2-6, 6-4 by Romania's Sorana Cirstea.

--Field Level Media