Guillermo Canas's highest singles ranking was 8th (June 2005). He started playing at age 7 and turned professional in 1995.
He plays a defensive counter-punching game from the baseline, and utilises his retrieving skills in order to frustrate opponents. He uses a double-handed backhand and his favourite surface is clay, but he is adept on hardcourt and grass too.
After a year of suspension for doping, Canas returned to the circuit on September 2006 at the challenger of Belem, Brazil. He holds a record of 5 victories and 2 defeats (3:1 in singles) in Davis Cup matches.