Former World No. 1 Naomi Osaka of Japan continued her return to dominance on Saturday, pulling off a 6-2, 7-6 (5) upset of 15th-seeded Ukrainian Elina Svitolina in the second round of the Miami Open in Miami Gardens, Fla.

After spending 15 months on maternity leave, Osaka returned to action at the Brisbane International at the start of the calendar year, where she was knocked out in the second round. She then failed to get past the first round at the Australian Open and the Mubadala Abu Dhabi Open but has since caught fire.

Osaka made it to the quarterfinals at the Qatar Open before putting together a third-round run at the BNP Paribas Open as she continued to hit her stride.

"Obviously, I want to win tournaments, but I know I have to take it one step at a time," Osaka said Saturday. "Just winning matches. The more matches I win, the more comfortable I'll be ... and hopefully that will lead to holding something above my head one day."

Against Svitolina, Osaka saved three of four break points and won 27 of 38 first-serve points. She also had five aces to Svitolina's two.

Osaka next faces No. 23 seed Caroline Garcia of France in the third round. Garcia was up 6-1, 5-2 when Bulgaria's Viktoriya Tomova retired on Saturday.

Garcia and Osaka have already met twice this year.

American Danielle Collins also pulled off an upset on Saturday, topping 30th-seeded Russian Anastasia Potapova 6-2, 6-2. Collins' countrywoman, No. 6 seed Jessica Pegula, also won, claiming a 6-4, 4-1 victory via walkover against China's Lin Zhu.

Pegula is now one step closer to reaching the Miami Open semifinals for the third straight year.

"Obviously, pretty good memories, tennis-wise," Pegula said of her time in Miami Gardens.

In the next round, Pegula will take on No. 31 seed Leylah Fernandez of Canada, a 6-4, 6-2 winner over Colombia's Emiliana Arango.

Russia's Elina Avanesyan also got the best of a seeded foe, clipping sixth-seeded Tunisian Ons Jabeur 6-1, 4-6, 6-3.

Meanwhile, Polish No. 1 seed Iga Swiatek hit the century mark in style, downing Italian Camila Giorgi 6-1, 6-1 in the 100th WTA 1000 match of her career.

Other winners Saturday included 27th-seeded Belarusian Victoria Azarenka, No. 26 seed Linda Noskova of the Czech Republic, Italian 12th seed Jasmine Paolini, No. 10 seed Daria Kasatkina of Russia and 19th-seeded Romanian Sorana Cirstea. Azarenka was playing a third-round match.

Also prevailing in third-round matches were Greek eighth seed Maria Sakkari, No. 22 seed Anna Kalinskaya of Russia, 24th seed Katie Boulter of Great Britain, 17th-seeded American Madison Keys, No. 32 seed Anhelina Kalinina of Ukraine and fourth seed Elena Rybakina and Yulia Putintseva, both of Kazakhstan.