Horacio Zeballos

He reached his first ATP Tour final at the St. Petersburg Open, defeating Yuri Schukin, Oleksandr Dolgopolov Jr., Ernests Gulbis and Igor Kunitsyn before falling in the final to Stakhovsky in a third-set tiebreak.

Zeballos started the singles season in a slump, falling in the first round four times, but had an excellent start to the doubles season. In his first tournament, the Heineken Open, Zeballos and Rogier Wassen defeated world no. 1 team Bob and Mike Bryan. Zeballos then reached the round of 16 at the Australian Open with countryman Leonardo Mayer, and reached the final at the Movistar Open with Italian Potito Starace. Zeballos then turned to the clay in the Copa Telmex in Argentina, where in the first round, he defeated countryman and former French Open champion Gastón Gaudio. It was Zeballos' first ATP singles win since he reached the final in St. Petersburg. Zeballos next defeated former world no. 1 Carlos Moyá and reached his first ATP quarterfinal since October, where he then lost to countryman Juan Mónaco. In doubles, Zeballos and countryman Sebastián Prieto were the fourth seeds and won the title against Simon Greul and Peter Luczak. It was Zeballos' first career ATP title. The next week, at the Abierto Mexicano Telcel, Zeballos lost in the first round to Łukasz Kubot. He made it to the doubles semifinals, with partner Mónaco.

Zeballos was selected for the Argentine Davis Cup team for the first time. He played doubles with David Nalbandian against the Swedish pair of Robert Lindstedt and Robin Söderling. They won in straight sets. Zeballos reached a career milestone as he defeated his first-ever top-25 player, 24th ranked Gilles Simon, in the second roun at the Sony Ericsson Open. He then lost in the third round to eventual finalist Tomáš Berdych.

At the US Men's Clay Court Championships, he defeated Taylor Dent, Dudi Sela, and world no. 11 Fernando González for his first top-15 win and the biggest one of his career. He then faced eventual champion Juan Ignacio Chela in the semifinals, where he lost in straight sets.

At the US Open, Zeballos with partner Eduardo Schwank reached the semifinals in doubles.

Zeballos played mostly on the Challenger circuit in singles. He did not make it past the second round in any ATP events. He had more success in doubles. In 2012, he made it to the semifinals in Viña de Mar and Buenos Aires. At Roland Garros, he and partner Oliver Marach made it to the quarterfinals, where they were beaten by the Bryan brothers.

Zeballos won his first ATP singles title at Viña del Mar, where he defeated Rafael Nadal in three sets in his comeback tournament.[2] This victory made Zeballos one of the only four players who have beaten Nadal in a final on clay (the others are Roger Federer, Novak Djokovic and Andy Murray).

Zeballos' first match in the 2017 Australian Open was a 5-hour and 15 minute loss to Ivo Karlović, the second longest match by time at the Australian Open in the Open Era.

At Roland Garros, he had his best performance at a Grand Slam, reaching the fourth round. He was beaten by 6th seed Dominic Thiem in straight sets.

Zeballos won his first ATP Masters 1000 Doubles Title at the 2019 BNP Paribas Open with Nikola Mektić. They defeated sixth-seeded Łukasz Kubot and Marcelo Melo in the final. Zeballos became the first ATP Masters doubles champion from Argentina since 1997 after Luis Lobo at the Hamburg Masters.