Sebastián Báez

Báez made his ATP debut at the 2021 Chile Open where he lost to 2019 Junior French Open champion Holger Rune in straight sets.

He earned his first tour-level win at the 2021 Hamburg European Open, where he defeated Frenchman Corentin Moutet in the first round.

Baez became the youngest player in history to claim five ATP Challenger Tour titles in a season, lifting the trophy in Concepción (d. F. Cerundolo), Santiago (d. Barrios Vera), Zagreb (d. Varillas), Santiago-3 (d. Meligeni Rodrigues Alves) and Buenos Aires (d. Monteiro). He qualified for the 2021 Next Generation ATP Finals in Milan after the withdrawal of Jenson Brooksby due to an abdominal injury.[2] Baez advanced to the semifinals with wins over third seed Lorenzo Musetti and eighth seed Hugo Gaston. He lost in the semifinals against top seed Carlos Alcaraz.[3][4][5]

He reached the top 100 for the first time in his career at World No. 97 in the ATP year-end rankings on 22 November 2021 after winning his sixth Challenger in Campinas, Brazil.[6]

Baez started the year in the 2022 Melbourne Summer Set 1 where he lost in the final round of qualifying and got in the main draw as a lucky loser. He was defeated by Emil Ruusuvuori in straight sets on the first round. The following week at the 2022 Sydney International, Baez got entry as a qualifier and defeated Christopher O'Connell in three sets. He lost in the second round to Lorenzo Sonego.

On his debut at the 2022 Australian Open he defeated Albert Ramos Viñolas for his first Grand Slam win in his career. In the second round he faced a top-10 opponent for the first time in his career, World No. 4 Stefanos Tsitsipas. He lost in four sets in a hard-fought match. As a result, he entered the top 80 at World No. 77 on 31 January 2022.

He reached his first ATP-level quarterfinal at the 2022 Córdoba Open, defeating Fernando Verdasco and World No. 18 and third seed Cristian Garín.[7] Baez received a wildcard in his hometown tournament, the 2022 Argentina Open, where he defeated Holger Rune and lost again to Lorenzo Sonego in the second round. The following week at the 2022 Rio Open, he surpassed the qualyifing stages with three-set wins against Nikola Milojević and Yannick Hanfmann. He was defeated by Thiago Monteiro in the first round.

At the 2022 Chile Open Baez was the 7th seed, the first time he was seeded in an ATP tournament. He reached his maiden ATP Tour final, defeating Juan Pablo Varillas, fellow countryman Juan Ignacio Londero, Thiago Monteiro and Albert Ramos Viñolas in the semifinals.[8] He lost to Pedro Martínez in the final. As a result, he reached the top 60 on 7 March 2022.

At the 2022 Estoril Open Baez reached the second semifinal of the season defeating third seed Marin Čilić and Richard Gasquet en route.[9] As a result of reaching the semifinals, he debuted in the top 50.[10][11] Next he defeated Albert Ramos Viñolas to reach his second final of the season and of his career.[12] He won his maiden title defeating third seed Frances Tiafoe and moved into the top 40 on 2 May 2022.[13]

He made his debut at the 2022 French Open and at the 2022 Wimbledon Championships and won his first match at each of the Majors defeating Dušan Lajović and Taro Daniel respectively.

He reached his third final at the 2022 Swedish Open in Båstad with a win over second seed, top-10 player Andrey Rublev,[14] where he lost to compatriot Francisco Cerúndolo.[15] He reached a career-high ranking of No. 32 on 18 July 2022.

In October seeded sixth, he defeated No. 50 Lorenzo Sonego at the 2022 Tennis Napoli Cup and snapped an 11-match losing streak.[16]

In February, he won the second title of his career at the Córdoba Open in Argentina, defeating Luciano Darderi, Tomás Barrios Vera, Hugo Dellien, and compatriot Federico Coria on clay.[17]

He reached the top 30 in the rankings on 17 April 2023 following the 2023 Monte-Carlo Masters.

In August, Báez won the third and fourth titles of his career as part of a ten-match winning streak. He won the singles title at the Austrian Open Kitzbühel on clay, defeating Dominic Thiem in the final in straight sets.[18] Next, he won the singles title at the 2023 Winston-Salem Open on hard courts, defeating Jiří Lehečka in the final also in straight sets.[19][20]

At the US Open he reached the third round of a Major for the first time defeating 27th seed Borna Ćorić and Felipe Meligeni Alves[21] before losing to eventual finalist and third seed Daniil Medvedev.[22]

Following the 2024 Australian Open where he reached a Grand Slam third round for the second time in his career, he moved to a new career-high into the top 25 in the singles rankings.

As the defending champion, at the 2024 Córdoba Open, he reached the semifinals for a second consecutive year[23] but lost to qualifier Luciano Darderi. Seeded fifth, he reached the biggest final of his career at the 2024 Rio Open defeating fourth seed and compatriot Francisco Cerúndolo.[24][25] He won his fifth and biggest title defeating qualifier and first time ATP finalist, compatriot Mariano Navone.[26] As a result he moved to a new career-high ranking of world No. 21 on 26 February 2024. The following week, at the 2024 Chile Open he won his second title of the season defeating home favorite Alejandro Tabilo. As a result he became the Latin American No. 1 player when he moved into the top 20 in the rankings at world No. 19.[27][28]