Sousa started the 2013 season with his first participation in ATP tour level hardcourt tournaments at the Chennai Open and the Sydney International.
Despite being knocked out of both tournaments in the first round, he returned to the top-100 world rankings.
At the Australian Open, Sousa won his first Grand Slam on his second attempt, following a first-round win over wildcard John-Patrick Smith.
He lost to world number three Andy Murray in straight sets in the second round.
In February, Sousa participated in the Portugal Davis Cup team in their Europe/Africa Zone Group II tie against Benin.
He won his singles match against Loic Didavi and the doubles match partnering with Pedro Sousa.
Portugal won the tie 5–0 and progressed to the second round.
Sousa then played his first clay court tournaments of the season at the Chile Open and ATP Buenos Aires, where he again lost in the first round.
At the Mexican Open, he defeated former top 10 Jürgen Melzer in the first round, but lost in the second round to Santiago Giraldo.

Despite failing to qualify for the Indian Wells Masters, Sousa entered for the first time in his career in the main draw of a Masters event at the Miami Masters.
He lost in the first round to former world number 1 Lleyton Hewitt in straight sets.
Sousa did not play in April after fracturing his left foot during a Davis Cup training session.
He was scheduled to return as a wild card at the Portugal Open.
His invitation was given to world number 4 David Ferrer instead, which stirred some controversy in Portuguese media.
Later in the season, Sousa showed uncertainties about his future Portugal Open participation, which prompted tournament director João Lagos to comment on the contention.
Ahead of the 2014 edition, the controversy was no longer an issue.

Sousa returned to action at the Madrid Masters qualifying rounds and at his first Challenger tournament of the season in Bordeaux, but he lost early in these attempts.
At the 2013 French Open, Sousa won his first round match over Go Soeda in straight sets, and lost in the second round to Spaniard Feliciano López.
He returned to the Challenger circuit with a singles title at Fürth and an early loss at Košice.
It was also his second title in Fürth, after the triumph in 2011.
Sousa missed the 2013 Wimbledon Championships main draw after losing in the third qualifying round to Julian Reister.
He would also lose in the qualifying rounds of the doubles competition, while partnering with Teymuraz Gabashvili.
In July, he played exclusively in Challenger tournaments, being runner-up in singles and doubles in San Benedetto, re-entering the top 100 rankings, which he has maintained ever since.
He won the singles title in his hometown Guimarães.
This remains his last participation at the ATP Challenger Tour, having won five singles and two doubles titles at the level.
After losing in the qualifying rounds of the Cincinnati Masters, Sousa returned to the ATP World Tour at the Winston-Salem Open in August, losing to Alex Bogomolov, Jr. in the second round.
In his first US Open appearance, Sousa reached the third round after defeating 25th seed Grigor Dimitrov and Jarkko Nieminen in back-to-back 5-set matches.
He ended his campaign losing to world No.
 1 Novak Djokovic.
This was his best result at Grand Slams yet.

In September, Sousa joined Portugal's Davis Cup team to face Moldova in the semifinals of Europe/Africa Zone Group II.
He won his first singles match over Maxim Dubarenco and the doubles match with Gastão Elias.
He lost his second singles match to Radu Albot in an epic five-set duel which lasted nearly five hours.
Portugal won 3–2 and was promoted to Group I in 2014.
 Following early-round wins over Paolo Lorenzi and Sergiy Stakhovsky at the St. Petersburg Open, Sousa beat former ATP top 20 player Dmitry Tursunov in the quarterfinals to advance to his first career ATP tour semifinal.
He would lose there to Guillermo García-López.

Sousa's breakthrough title came at the Malaysian Open, in the early rounds of which he defeated Ryan Harrison and Pablo Cuevas.
In the quarterf
Sousa started the 2013 season with his first participation in ATP tour level hardcourt tournaments at the Chennai Open and the Sydney International. Despite being knocked out of both tournaments in the first round, he returned to the top-100 world rankings. At the Australian Open, Sousa won his first Grand Slam on his second attempt, following a first-round win over wildcard John-Patrick Smith. He lost to world number three Andy Murray in straight sets in the second round. In February, Sousa participated in the Portugal Davis Cup team in their Europe/Africa Zone Group II tie against Benin. He won his singles match against Loic Didavi and the doubles match partnering with Pedro Sousa. Portugal won the tie 5–0 and progressed to the second round. Sousa then played his first clay court tournaments of the season at the Chile Open and ATP Buenos Aires, where he again lost in the first round. At the Mexican Open, he defeated former top 10 Jürgen Melzer in the first round, but lost in the second round to Santiago Giraldo.
Despite failing to qualify for the Indian Wells Masters, Sousa entered for the first time in his career in the main draw of a Masters event at the Miami Masters. He lost in the first round to former world number 1 Lleyton Hewitt in straight sets. Sousa did not play in April after fracturing his left foot during a Davis Cup training session. He was scheduled to return as a wild card at the Portugal Open. His invitation was given to world number 4 David Ferrer instead, which stirred some controversy in Portuguese media. Later in the season, Sousa showed uncertainties about his future Portugal Open participation, which prompted tournament director João Lagos to comment on the contention. Ahead of the 2014 edition, the controversy was no longer an issue.
Sousa returned to action at the Madrid Masters qualifying rounds and at his first Challenger tournament of the season in Bordeaux, but he lost early in these attempts. At the 2013 French Open, Sousa won his first round match over Go Soeda in straight sets, and lost in the second round to Spaniard Feliciano López. He returned to the Challenger circuit with a singles title at Fürth and an early loss at Košice. It was also his second title in Fürth, after the triumph in 2011. Sousa missed the 2013 Wimbledon Championships main draw after losing in the third qualifying round to Julian Reister. He would also lose in the qualifying rounds of the doubles competition, while partnering with Teymuraz Gabashvili. In July, he played exclusively in Challenger tournaments, being runner-up in singles and doubles in San Benedetto, re-entering the top 100 rankings, which he has maintained ever since. He won the singles title in his hometown Guimarães. This remains his last participation at the ATP Challenger Tour, having won five singles and two doubles titles at the level. After losing in the qualifying rounds of the Cincinnati Masters, Sousa returned to the ATP World Tour at the Winston-Salem Open in August, losing to Alex Bogomolov, Jr. in the second round. In his first US Open appearance, Sousa reached the third round after defeating 25th seed Grigor Dimitrov and Jarkko Nieminen in back-to-back 5-set matches. He ended his campaign losing to world No. 1 Novak Djokovic. This was his best result at Grand Slams yet.
In September, Sousa joined Portugal's Davis Cup team to face Moldova in the semifinals of Europe/Africa Zone Group II. He won his first singles match over Maxim Dubarenco and the doubles match with Gastão Elias. He lost his second singles match to Radu Albot in an epic five-set duel which lasted nearly five hours. Portugal won 3–2 and was promoted to Group I in 2014.  Following early-round wins over Paolo Lorenzi and Sergiy Stakhovsky at the St. Petersburg Open, Sousa beat former ATP top 20 player Dmitry Tursunov in the quarterfinals to advance to his first career ATP tour semifinal. He would lose there to Guillermo García-López.
Sousa's breakthrough title came at the Malaysian Open, in the early rounds of which he defeated Ryan Harrison and Pablo Cuevas. In the quarterf
João Sousa