João Sousa trained with Rafael Nadal in the offseason for the second year running.
He started the 2017 season at the Auckland Open once again, where he reached the final after beating Albert Ramos-Vinolas, Brydan Klein, Robin Haase and Marcos Baghdatis.
He lost in three sets to Jack Sock, but the result allowed him to re-enter the Top 40 in the ATP Singles Rankings.
Sousa's January ended with a first-round exit at the Australian Open, having lost in five sets to Jordan Thompson, his worst result at this Grand Slam since 2014.

Sousa started the South American swing at the Argentina Open, having lost in the quarter-finals to eventual finalist Kei Nishikori.
At the Rio Open, Sousa crashed out in the first round, losing in two sets to Roberto Carballes Baena, in a match that lasted just under an hour.
His last clay tournament in South America was the Brasil Open, where he lost in the semi-finals to Albert Ramos-Vinolas in three sets.

In March, Sousa entered the first two Masters 1000 tournaments of the season.
At the BNP Paribas Open, he lost to Mischa Zverev in the second round.
At the Miami Open, Sousa entered as 30th seed, receiving a bye for the first round, but lost in the second round to Fabio Fognini.

Sousa's late May ended with second round at the French Open, having lost to three sets to Serbian number 2's Novak Djokovic by 6–1, 6–4, 6–3.
But, Sousa already won at first round with Serbia's Janko Tipsarevic, having won by four sets by 4–6, 7–6 (7–3), 6–2, 6–2.

After the clay court season was over, he continued a streak of consecutive losses, losing matches to Philipp Kohlschreiber, Radu Albot and Dustin Brown at the Gerry Weber Open, Antalya Open and Wimbledon respectively.

Sousa's streak remained active in Croatia Open Umag, losing in 3 sets to Aljaz Bedene.
However, he would eventually turn it around winning by reaching the quarterfinals in Swiss Open Gstaad and reaching the final in Generali Open Kitzbühel.

He would go on to have more losses in the remainder of the year and not many more wins.
One of these includes two crucial defeats in the Davis Cup where Portugal could have qualified for the World Group for the first time in its history, specially considering the absence of the Zverev brothers and Kohlschreiber.
João Sousa trained with Rafael Nadal in the offseason for the second year running. He started the 2017 season at the Auckland Open once again, where he reached the final after beating Albert Ramos-Vinolas, Brydan Klein, Robin Haase and Marcos Baghdatis. He lost in three sets to Jack Sock, but the result allowed him to re-enter the Top 40 in the ATP Singles Rankings. Sousa's January ended with a first-round exit at the Australian Open, having lost in five sets to Jordan Thompson, his worst result at this Grand Slam since 2014.
Sousa started the South American swing at the Argentina Open, having lost in the quarter-finals to eventual finalist Kei Nishikori. At the Rio Open, Sousa crashed out in the first round, losing in two sets to Roberto Carballes Baena, in a match that lasted just under an hour. His last clay tournament in South America was the Brasil Open, where he lost in the semi-finals to Albert Ramos-Vinolas in three sets.
In March, Sousa entered the first two Masters 1000 tournaments of the season. At the BNP Paribas Open, he lost to Mischa Zverev in the second round. At the Miami Open, Sousa entered as 30th seed, receiving a bye for the first round, but lost in the second round to Fabio Fognini.
Sousa's late May ended with second round at the French Open, having lost to three sets to Serbian number 2's Novak Djokovic by 6–1, 6–4, 6–3. But, Sousa already won at first round with Serbia's Janko Tipsarevic, having won by four sets by 4–6, 7–6 (7–3), 6–2, 6–2.
After the clay court season was over, he continued a streak of consecutive losses, losing matches to Philipp Kohlschreiber, Radu Albot and Dustin Brown at the Gerry Weber Open, Antalya Open and Wimbledon respectively.
Sousa's streak remained active in Croatia Open Umag, losing in 3 sets to Aljaz Bedene. However, he would eventually turn it around winning by reaching the quarterfinals in Swiss Open Gstaad and reaching the final in Generali Open Kitzbühel.
He would go on to have more losses in the remainder of the year and not many more wins. One of these includes two crucial defeats in the Davis Cup where Portugal could have qualified for the World Group for the first time in its history, specially considering the absence of the Zverev brothers and Kohlschreiber.
João Sousa