Sebastián Báez (Spanish pronunciation: [seβasˈtjam ˈbaes];[a] born 28 December 2000) is an Argentine professional tennis player.

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).

[7] 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.

[8] 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.

At the 2022 Estoril Open Baez reached the second semifinal of the season defeating third seed Marin Čilić and Richard Gasquet en route.

[14] 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,[15] where he lost to compatriot Francisco Cerúndolo.

[17] 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.

He won the singles title at the Austrian Open Kitzbühel on clay, defeating Dominic Thiem in the final in straight sets.

[19][20] 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.

[24] 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.