Iga Swiatek started her week by deciding that she wanted to set her sights on becoming the No. 1 player in the world, without knowing how long that quest would take. (More Tennis News)

A few days and one surprising retirement later, mission accomplished.

Women's tennis has a new name atop its rankings, a 20-year-old who — now that Ashleigh Barty has retired and asked to vacate her No. 1 spot on the world list — becomes the first Polish player to hold that distinction.?

Swiatek's ascension was clinched Friday night with a 6-2, 6-0 win over Viktorija Golubic of Switzerland in the second round of the Miami Open.

When the tournament ends and the rankings are updated, Barty will be removed and Swiatek officially will move into the top spot no matter what happens the rest of the way in Miami.

Swiatek becomes the 28th different woman to hold the No. 1 ranking since the computerized system debuted in November 1975. Her rise has been steady and constant; she ended 2016 ranked No. 903, cracked the top 500 for the first time in 2018, ended 2020 ranked No. 17, then was No. 9 when last year ended.

Barty revealed her retirement decision on Wednesday, and as part of that said she wanted to be removed from the rankings. She's held the top spot for 113 consecutive weeks, tying Chris Evert for the fourth-longest such streak ever.?

And Barty, the two-time defending champion in Miami, would have kept the top spot after this tournament ended even if Swiatek won the title.

But her decision to retire and step out of the rankings opened the door for either Swiatek or Paula Badosa, the No. 5 seed in Miami and the only other person who had a mathematical chance of getting the top spot.?

Badosa won her second-rounder in Miami on Friday, topping Marie Bouzkova 7-5, 7-5 in a match that ended shortly before Swiatek took the court.

Swiatek and Badosa bucked a wild trend in Miami — where seeded women's players have had serious struggles. There were 32 seeds entering the tournament, and more than half of them are gone before the third round even gets started.

Coco Gauff is one of the few exceptions.

The 14th-seeded American, whose home is about a 45-minute drive north from where she's playing this event, got past Wang Qiang of China 7-5, 6-4 on Friday — avenging a first-round loss to her in the Australian Open earlier this year.

"I feel like playing at a home crowd you either can get nervous playing in front of your family, friends, or embrace it," Gauff said.?

"And today I think I embraced it."?

No. 16 Jessica Pegula felt right at home too, even though the tournament is held on the grounds where the NFL's Miami Dolphins practice and play — and her parents, Terry and Kim Pegula, just happen to own the Dolphins' AFC East rival Buffalo Bills. Pegula had little trouble beating 2018 Miami Open winner Sloane Stephens 6-1, 6-4.

"It is weird," Pegula said about playing at the Dolphins' home.

No. 4 Maria Sakkari of Greece, No. 10 Jelena Ostapenko of Latvia, No. 20 Elise Mertens of Belgium, No. 24 Sorana Cirstea of Romania, and No. 29 Liudmila Samsonova of Russia all lost second-round matches Friday.

Their defeats meant 16 seeded women have now lost their opening matches at the tournament.?

Another four seeded women have withdrawn with either injuries or ailments, meaning no more than 12 of the original 32 seeds will get to the third round that starts Saturday.

Shelby Rogers of the U.S. used 15 aces — and saved nine of the 10 break points she faced — to beat Ostapenko, 6-3, 7-6 (0). It was Rogers' second win over Ostapenko this month, after also topping her in a second-round matchup at Indian Wells.

"There are no easy matches out here," said Rogers, who has now made the third round at Miami for just the second time; she also did it in 2017.

Beatriz Haddad Maia of Brazil topped Sakkari 4-6, 6-1, 6-2. Madison Brengle of the U.S. beat Samsonova 6-4, 6-0. China's Zhang Shuai needed only 53 minutes to beat Cirstea, 6-1, 6-1. Linda Fruhvirtova of the Czech Republic topped Mertens 7-5, 2-6, 6-1.

Other seeded second-round women's winners Friday included No. 17 Elena Rybakina, No. 21 Veronika Kudermetova and No. 28 Petra Kvitova.

In men's second-round play, a pair of seeded American men were ousted. No. 16 Reilly Opelka retired from his match against Argentina's Francisco Cerundolo with a shoulder injury, and Hugo Gaston knocked out No. 20 John Isner 7-6 (5), 6-4. Isner — the 2018 Miami champion — had 22 aces and was broken just once, but went 0 for 5 on his break chances.

No. 2 seed Alexander Zverev was tested but topped 166th-ranked Borna Coric 6-4, 3-6, 6-3, and said getting more aggressive as the match went along was key.

"I felt like, OK, if I'm going to lose, I'm going to go for it,'" Zverev said.?

"It worked out."?

Fan favorite Nick Kyrgios rolled past No. 5 Andrey Rublev 6-3, 6-0, and No. 9 Jannik Sinner dug way deep to hold off Emil Ruusuvuori 6-4, 3-6, 7-6 (8).

No. 10 Cameron Norrie improved to 12-2 in his past 14 outings by beating fellow British player Jack Draper in straight sets. No. 17 Pablo Carreno Busta and No. 31 Fabio Fognini also prevailed, but No. 13 Diego Schwartzman lost a three-setter to Thanasi Kokkinakis and No. 19 Lorenzo Sonego of Italy lost to Denis Kudla of the U.S. in three sets.