2008 Mutua Madrileña Masters Madrid, losing to Radek Štěpánek, and the 2008 Grand Prix de Tennis de Lyon to Gilles Simon. He reached the second round of both the 2008 Stockholm Open and the 2008 BNP Paribas Masters after qualifying for both tournaments. Monaco ended the year ranked no. 46 in the world, 23 places lower than his year-end ranking in 2007. In doubles, Monaco started the year with a win in the 2008 Heineken Open partnering Luis Horna. He reached the semifinals of 2008 US Open, losing to Lukáš Dlouhý and Leander Paes. He also reached the final of the 2008 Movistar Open and won the 2008 Open de Tenis Comunidad Valenciana, all partnering fellow Argentine Máximo González. 2009 In 2009, Monaco started the year in 2009 Heineken Open losing to Serbian Viktor Troicki in the second round and a quarterfinal appearance in the 2009 Movistar Open. He lost in the first round of 2009 Brasil Open, the 2009 Australian Open, and Acapulco. He reached his first final of the year in Buenos Aires at the 2009 Copa Telmex, losing to Tommy Robredo in a tight three-setter. In doubles, he reached the third round of the 2009 Australian Open and the final of 2009 Brasil Open, both partnering Lucas Arnold Ker He represented Argentina in the Davis Cup, defeating Thiemo de Bakker of the Netherlands. He also reached the second round of the 2009 Sony Ericsson Open, losing to Andy Murray after winning the first set. He also reached the third round of the 2009 Monte-Carlo Rolex Masters, losing to German Andreas Beck, after defeating Tommy Robredo in the second round, and the 2009 Barcelona Open Banco Sabadell losing to Fernando González after defeating Marat Safin in the first round. He reached his first Masters quarterfinal at the 2009 Internazionali BNL d'Italia, entering as a qualifier and beating Andy Murray in the second round, Marin Čilić in the third round, but losing to Fernando González. He also reached the round of 16 at the 2009 Estoril Open and the 2009 Mutua Madrileña Madrid Open, where he faced three Spaniards losing to Fernando Verdasco after defeating Feliciano López and David Ferrer. 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. He reached the second round of Roland Garros,