(Photo credit: Aaron Doster-Imagn Images)

Greece's Stefanos Tsitsipas didn't win a single match as the defending champion of the Dubai Duty Free Tennis Championships, falling to the man who preceded him as the champion in the United Arab Emirates.

France's Ugo Humbert beat Tsitsipas 6-4, 7-5 on Tuesday in first-round action.

Humbert saved all three break points he faced in a match that saw the players nearly equal each other statistically. Humbert finished with a 7-6 edge in aces, Tsitsipas committed one more unforced error than his foe (20-19), and each player totaled 16 winners.

Second-seeded Alexander Bublik of Kazakhstan, third-seeded Daniil Medvedev and fifth-seeded Andrey Rublev of Russia, and sixth-seeded Jakub Mensik of the Czech Republic won in straight sets. Seventh-seeded Russian Karen Khachanov and eighth-seeded Czech Jiri Lehecka both rallied from one set down to prevail in three.

The United States' Jenson Brooksby, Spanish qualifier Pablo Carreno Busta, the Netherlands' Tallon Griekspoor, Australia's Alexei Popyrin and France's Arthur Rinderknech also advanced.

BCI Seguros Chile Open

Eighth-seeded Alejandro Tabilo emerged on top in an all-Chilean matchup, defeating Tomas Barrios Vera 7-5, 6-3 in the first round at Santiago, Chile.

Tabilo fired seven aces and had no double faults, while Barrios Vera logged twice as many double faults as aces (4-2).

Emilio Nava upset sixth-seeded Matteo Berrettini of Italy 6-3, 6-4, with the U.S. player saving all three break points he faced. Chile's Cristian Garin, the 2021 Santiago champion, rallied past Argentina's Juan Manuel Cerundolo 3-6, 6-3, 6-3.

Also earning first-round wins were Lithuania's Vilius Gaubas, Denmark's Elmer Moller, Argentina's Mariano Navone and Thiago Agustin Tirante, and Paraguayan qualifier Adolfo Daniel Vallejo.

--Field Level Media