Nadal opened his season by playing at the Brisbane International for the first time, where he reached the quarterfinals before losing to Milos Raonic in three sets.
In the second round of the tournament, he defeated Mischa Zverev for the loss of just two games;  Nadal began the Australian Open with straight-set wins over Florian Mayer and Marcos Baghdatis, before more difficult wins over Alexander Zverev and Gael Monfils, which set up his first quarterfinal berth at a Grand Slam since the 2015 French Open.
Nadal defeated Raonic and Grigor Dimitrov in the quarterfinal and semifinal, respectively (the latter lasting for five sets over five hours), to set up a final against Roger Federer, his first Grand Slam final since he won the 2014 French Open.
Nadal went on to lose to Federer in five sets; this was the first time that Nadal had lost to Federer in a Grand Slam since the final of the 2007 Wimbledon Championships.

Nadal made it to the final of Acapulco without dropping a set, but was defeated by big-serving Sam Querrey.
In a rematch of the Australian Open final Nadal took on Roger Federer in the fourth round at Indian Wells but again lost to his old rival, this time in straight sets; it was their earliest meeting in a tournament in over a decade.
In the Miami Masters, Nadal reached the final to again play Federer, and was once again defeated in straight sets.
Nadal then won his 29th Masters 1000 title in Monte Carlo; it was his tenth victory in the principality, the most wins by any player at a single tournament in the Open era.

Nadal won his 18th ATP 500 title in Barcelona without dropping a set, also marking his tenth victory in Barcelona.
Nadal next played in the Madrid Open, where he defeated Dominic Thiem to tie Novak Djokovic's all-time Masters record of 30 titles.

Nadal went on to beat Stan Wawrinka in straight sets and win a record tenth French Open title.
This marked his first Grand Slam title since 2014, ending his three-year drought in Grand Slams.
Nadal won every set that he played in the tournament, dropping a total of only 35 games over his seven matches, which is the second-fewest by any male (second only to Björn Borg's 32 dropped games at the 1978 French Open) on the way to a title at a Grand Slam tournament in the Open era with all matches being best-of-five-sets.
The achievement, called "La Décima" ("the tenth" in Spanish), made Nadal the first male or female in the Open era to win ten titles from a single Grand Slam tournament, following similar achievements in Monte Carlo and Barcelona.
Nadal also climbed to second on the all-time Grand Slam titles list, with 15 grand slam championships, putting him one ahead of Pete Sampras.

Nadal lost in the round of 16 at Wimbledon, 13–15 in the fifth set, to Gilles Müller.
He returned to competition in Montreal.
He won his first match against Coric in straight sets but fell in the Round of 16 to Canadian teenager Denis Shapovalov.
By 21 August, he retook the ATP No.
1 ranking from Andy Murray.
Nadal earned his third US Open title against first-time Grand Slam finalist Kevin Anderson, winning the final in straight sets.
This marked the first time that Nadal had captured two Grand Slam tournaments in a year since 2013, and the second time since 2010.
Nadal extended his winning streak by winning the China Open, winning the final against Nick Kyrgios in straight sets.
On 11 September 2017, Nadal and Garbiñe Muguruza made Spain the first country since the United States 14 years ago to simultaneously top both the ATP and the WTA rankings, with Muguruza making her debut in the No.
1 spot.

After defeating Hyeon Chung in the second round of the Paris Masters Nadal secured the year-end No.
1.
He became year-end No.
1 for the fourth time in his career, tying him for fourth all-time with Novak Djokovic, Ivan Lendl and John McEnroe, behind Pete Sampras (6), and Roger Federer and Jimmy Connors (5).
By securing the year-end no.
1 ranking, Nadal became the first player aged over 30 to finish as year-end No.
1 and the first to finish in the top spot four years since he last achie
Nadal opened his season by playing at the Brisbane International for the first time, where he reached the quarterfinals before losing to Milos Raonic in three sets. In the second round of the tournament, he defeated Mischa Zverev for the loss of just two games;  Nadal began the Australian Open with straight-set wins over Florian Mayer and Marcos Baghdatis, before more difficult wins over Alexander Zverev and Gael Monfils, which set up his first quarterfinal berth at a Grand Slam since the 2015 French Open. Nadal defeated Raonic and Grigor Dimitrov in the quarterfinal and semifinal, respectively (the latter lasting for five sets over five hours), to set up a final against Roger Federer, his first Grand Slam final since he won the 2014 French Open. Nadal went on to lose to Federer in five sets; this was the first time that Nadal had lost to Federer in a Grand Slam since the final of the 2007 Wimbledon Championships.
Nadal made it to the final of Acapulco without dropping a set, but was defeated by big-serving Sam Querrey. In a rematch of the Australian Open final Nadal took on Roger Federer in the fourth round at Indian Wells but again lost to his old rival, this time in straight sets; it was their earliest meeting in a tournament in over a decade. In the Miami Masters, Nadal reached the final to again play Federer, and was once again defeated in straight sets. Nadal then won his 29th Masters 1000 title in Monte Carlo; it was his tenth victory in the principality, the most wins by any player at a single tournament in the Open era.
Nadal won his 18th ATP 500 title in Barcelona without dropping a set, also marking his tenth victory in Barcelona. Nadal next played in the Madrid Open, where he defeated Dominic Thiem to tie Novak Djokovic's all-time Masters record of 30 titles.
Nadal went on to beat Stan Wawrinka in straight sets and win a record tenth French Open title. This marked his first Grand Slam title since 2014, ending his three-year drought in Grand Slams. Nadal won every set that he played in the tournament, dropping a total of only 35 games over his seven matches, which is the second-fewest by any male (second only to Björn Borg's 32 dropped games at the 1978 French Open) on the way to a title at a Grand Slam tournament in the Open era with all matches being best-of-five-sets. The achievement, called "La Décima" ("the tenth" in Spanish), made Nadal the first male or female in the Open era to win ten titles from a single Grand Slam tournament, following similar achievements in Monte Carlo and Barcelona. Nadal also climbed to second on the all-time Grand Slam titles list, with 15 grand slam championships, putting him one ahead of Pete Sampras.
Nadal lost in the round of 16 at Wimbledon, 13–15 in the fifth set, to Gilles Müller. He returned to competition in Montreal. He won his first match against Coric in straight sets but fell in the Round of 16 to Canadian teenager Denis Shapovalov. By 21 August, he retook the ATP No. 1 ranking from Andy Murray. Nadal earned his third US Open title against first-time Grand Slam finalist Kevin Anderson, winning the final in straight sets. This marked the first time that Nadal had captured two Grand Slam tournaments in a year since 2013, and the second time since 2010. Nadal extended his winning streak by winning the China Open, winning the final against Nick Kyrgios in straight sets. On 11 September 2017, Nadal and Garbiñe Muguruza made Spain the first country since the United States 14 years ago to simultaneously top both the ATP and the WTA rankings, with Muguruza making her debut in the No. 1 spot.
After defeating Hyeon Chung in the second round of the Paris Masters Nadal secured the year-end No. 1. He became year-end No. 1 for the fourth time in his career, tying him for fourth all-time with Novak Djokovic, Ivan Lendl and John McEnroe, behind Pete Sampras (6), and Roger Federer and Jimmy Connors (5). By securing the year-end no. 1 ranking, Nadal became the first player aged over 30 to finish as year-end No. 1 and the first to finish in the top spot four years since he last achie
Rafael Nadal