Guilherme Clezar mainly plays on the ATP Challenger Tour , but occasionally also on the ATP World Tour . So far he has celebrated two individual victories on the Challenger Tour. In May 2012 he won the $ 35,000 tournament in Rio Quente against Chilean Paul Capdeville in straight sets and in 2013 the tournament in Campinas . He played his first game on the World Tour in February 2011 at the Brasil Open in Costa do Sauípe . He lost his first round game against his compatriot João Souza in straight sets with 3: 6 and 2: 6.
On April 22, 2013, he broke through the top 200 in the world rankings for the first time in singles and his highest ranking was 153rd on August 3, 2015. In doubles, he broke through the top 200 for the first time on April 22, 2013 and reached 171 as the best value. 1st place on August 15, 2016.