Juan Mónaco (Spanish pronunciation: [ˈxwam ˈmonako];[1][a] born 29 March 1984), nicknamed "Pico", is an Argentine former professional tennis player.

He made his Grand Slam debut in the 2004 French Open as a qualifier, losing in the second round to eventual finalist and compatriot Guillermo Coria.

He got his best result of the year reaching his first semifinal in 2004 Idea Prokom Open in Sopot (l. to José Acasuso) and 2004 Campionati Internazionali di Sicilia in Paloma (l. to Filippo Volandri).

Following the semifinal appearance, he lost four straight matches in Acapulco, the 2006 NASDAQ-100 Open, the 2006 U.S. Men's Clay Court Championships, and Morocco.

Following these losses, Mónaco achieved great results in the next four weeks, reaching the quarterfinals in Poertschach (l. to Luis Horna), the third round of Roland Garros (l. to Ivan Ljubičić), and the semifinals of the 2006 Mercedes Cup (l. to José Acasuso).

He also reached the quarterfinals of the 2007 U.S. Men's Clay Court Championships, losing to American James Blake and at the 2007 Estoril Open (l. to Paul-Henri Mathieu).

He qualified for the Hamburg Masters, but lost to top seed and eventual champion Roger Federer in the second round in three tight sets.

Following his good performance against Federer, he went on to compete in the 2007 Hypo Group Tennis International in Pörtschach and won the title against Gaël Monfils.

He won his third title of the year in the 2007 Austrian Open[4] in Kitzbühel after defeating the top seed Tommy Robredo in the quarterfinals and Potito Starace in the final.

At the Beijing Olympics, Mónaco lost to Marin Čilić in three tight sets 4–6, 7–6(7-5), 3–6, followed by successive defeats at the 2008 Pilot Pen Tennis and the 2008 US Open.

He also represented Argentina along with Juan Martín del Potro and Máximo González at the 2009 ARAG World Team Cup, where he won his only singles match against Serbian Janko Tipsarević.

At the 2009 BCR Open Romania, Mónaco reached his third final of the year, but once again ended as runner-up to Albert Montañés, after defeating qualifiers Júlio Silva and Pere Riba, eighth seed Pablo Cuevas, and German Simon Greul.

Mónaco started 2010 with the Heineken Open, where he defeated Horacio Zeballos in the first round, but lost to eventual champion John Isner in three sets.

He lost to sixth seed Nikolay Davydenko in the third round of the 2010 Australian Open, having defeated Ernests Gulbis and Michaël Llodra in five sets.

He lost to Thomaz Bellucci in the final of the 2010 Movistar Open, after defeating Nicolas Massú, Juan Ignacio Chela, Peter Luczak, and João Souza.

He lost to Juan Carlos Ferrero in the semifinals of the 2010 Copa Telmex just hours after defeating Horacio Zeballos in the quarterfinals, where he did not face a single break point.

He defeated top seed Fernando Verdasco in the quarterfinals, Juan Ignacio Chela for the second time in as many weeks, and Alberto Martín.

His bad run continued as he was upset by Daniel Gimeno Traver in the first round as the tenth seed of the 2010 Barcelona Open Banco Sabadell.

In the South American clay season, he fell in the first round of 2011 Movistar Open to Máximo González and the quarterfinals of the 2011 Copa Claro and 2011 Abierto Mexicano Telcel, losing to Stanislas Wawrinka and David Ferrer, respectively.

He then lost three matches in a row, starting with the 2011 Davis Cup semifinal, in a dead rubber he retired to Janko Tipsarević after losing the first set 6–2, and the first round of the 2011 Rakuten Japan Open Tennis Championships and the 2011 Shanghai Rolex Masters.

He then reached his first final in over a year and a half at the 2011 Valencia Open 500, but lost to Marcel Granollers after upsetting Nicolás Almagro in the first round and David Ferrer in the semifinals.

He then continued his success at the 2011 BNP Paribas Masters, with wins over Gilles Simon and Mardy Fish, before losing to Roger Federer in the quarterfinals.

He then played at the 2012 Monte-Carlo Rolex Masters, where he retired due to a right ankle injury in his first-round match against Robin Haase while leading by a break in the third.

Juan Mónaco then played the 2012 MercedesCup, he cruised past Tobias Kamke and Pavol Červenák in straight sets after receiving a bye in the first round.

[15] In doubles, he played with Rafael Nadal in his comeback and reached the final of the VTR Open, losing to Italians Paolo Lorenzi and Potito Starace.

In the Davis Cup quarterfinals against France, he hit back with a solid win over Gilles Simon in the second rubber, but lost his second match to Jo-Wilfried Tsonga.

He was the defending champion at the U.S. Men's Clay Court Championships, but in a rematch of the previous year's final, he lost to John Isner.

However, Mónaco bounced back, beating Jarkko Nieminen to win the inaugural Power Horse Cup, which was his first title of the year.

At the 2014 Shanghai Rolex Masters, he defeated João Sousa and eighth-seeded Milos Raonic to reach the third round, where he lost to Mikhail Youzhny.

He had continued success on the South American clay courts at the Argentina Open, making it to the final against Rafael Nadal, but unable to overcome him.