Fernandes won the Boys' Singles division of the 2010 Australian Open, defeating Sean Berman of Australia in the final, 7–5, 6–3.

He reached the semifinals in the Junior US Open doubles competition with his compatriot Guilherme Clézar, defeating the top seeds, Márton Fucsovics and Mate Zsiga in the second round.

He lost in the first round of qualifying at the Prime Cup Aberto de São Paulo challenger and the Brasil Open in Costa do Sauípe and U.S. Men's Clay Court Championships in Houston, ATP 250 events.

To prepare for the junior Wimbledon Championships, Fernandes played at the UNICEF Open, losing in the first round of qualifying to Aisam-ul-Haq Qureshi, 1–6, 5–7.

He received a wild card in to the main draw in the 2010 Copa Petrobras São Paulo challenger, coming back from a set and a break deficit to defeat fellow Brazilian Augusto Meirelles to win 3–6, 7–5, 6–0, saving three match points.

As the winner of the junior slam the previous year, Fernandes received a wild card into the 2011 Australian Open qualifying draw, suffering a leg injury in his 2–6, 0–6 loss to Evgeny Korolev.

Fernandes received a wild card into the main draw at the 2011 Pernambuco Brasil Open Series, and faced lucky loser Tiago Lopes, defeating him 6–4, 4–6, 6–2.

Citing fatigue and back pain, he withdrew from the final against Tatsuma Ito, and will instead prepare for his next tournament, the 2011 Aberto Santa Catarina De Tenis.