effort to Thiemo de Bakker. He then lost in the first round of 2010 Pilot Pen Tennis, the US Open, and the 2010 Rakuten Japan Open Tennis Championships. In October, he reached an ATP World Tour Masters 1000 semifinal for the first time in the 2010 Shanghai Rolex Masters 1000 by defeating Florent Serra 6–4, 7–6 Thiemo de Bakker 2–6, 6–3, 6–4, Mischa Zverev 6–2, 6–0 and Jürgen Melzer 6–7, 7–5, 6–2, but then lost to World No. 4 Andy Murray 6–4, 6–1. At the 2010 Valencia Open 500 he upset defending champion Andy Murray 6–2, 3–6, 6–2 in the second round but was then upset by Marcel Granollers 1–6, 6–3, 6–4 in the following round. Monaco, played his last tournament of the year at the BNP Paribas Masters where he defeated Sam Querrey 6–2, 7–6 but fell to no. 2 seed Novak Djokovic 6–4, 6–3 in the second round after failing to convert 7 of 8 break points. 2011 Monaco began his 2011 season at the 2011 Heineken Open as the fifth seed, but was upset by Adrian Mannarino. At the first Grand Slam of the year the Australian Open, he was upset by Robin Haase in the second round. 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. At the 2011 BNP Paribas Open, he was upset by American qualifier Ryan Sweeting in the second round after receiving a bye in the first round. At the 2011 Sony Ericsson Open, he fell to third seed Roger Federer in the third round. In the European clay season, Monaco didn't have a lot of success. At the 2011 Monte-Carlo Rolex Masters, he lost to Jo-Wilfried Tsonga. He then fell in the second round of the 2011 Barcelona Open Banco Sabadell to Simone Vagnozzi. He then lost to Feliciano López in the first round of the 2011 Serbia Open. At the 2011 Mutua Madrid Open and 2011 Internazionali BNL d'Italia, he lost to Tomáš Berdych on both occasions, in the third round and second round, respectively. He then represented Argentina at the 2011 Power Horse World Team Cup, where they fell in the final to Germany. At Roland Garros, Monaco suffered a first-round exit at the hands of Fernando Verdasco.