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.
At Wimbledon, he lost in five sets to Mikhail Youzhny in the first round.

He then represented Argentina at the 2011 Davis Cup quarterfinal against Kazakhstan and won both his matches.
He then had to withdraw from the second round 2011 Swedish Open due to a foot injury.
At the 2011 International German Open, he reached the third round, losing to Florian Mayer.
He then fell early at the 2011 Rogers Cup and 2011 Western & Southern Open.
He then played at the 2011 Winston-Salem Open, losing to Andy Roddick in the quarterfinals.
Monaco reached the fourth round of the US Open, before losing to Federer.
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 finished the year no.
26 in the world.
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. At Wimbledon, he lost in five sets to Mikhail Youzhny in the first round.
He then represented Argentina at the 2011 Davis Cup quarterfinal against Kazakhstan and won both his matches. He then had to withdraw from the second round 2011 Swedish Open due to a foot injury. At the 2011 International German Open, he reached the third round, losing to Florian Mayer. He then fell early at the 2011 Rogers Cup and 2011 Western & Southern Open. He then played at the 2011 Winston-Salem Open, losing to Andy Roddick in the quarterfinals. Monaco reached the fourth round of the US Open, before losing to Federer. 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 finished the year no. 26 in the world.
Juan Mónaco