Guillermo is good friends with fellow Spanish tennis player Juan Carlos Ferrero and both train at the JC Ferrero Equelite Tennis Academy in Villena, Spain.
On June 22, 2009, Garcia-Lopez achieved his career-high singles ranking: World No. 42. Garcia-Lopez lost to Roger Federer in 2R of Wimbledon 2009 2-6 2-6 4-6.