Nadal started the year playing at the Brisbane International for the first time, where he reached the quarterfinals before losing to Milos Raonic in three sets.
At the Australian Open, Nadal made it to the quarterfinal berth at a Grand Slam for the first time since the 2015 French Open. He faced tough opponents like Alexander Zverev, Gael Monfils, Milos Raonic and Grigor Dimitrov before losing to Roger Federer, his first Grand Slam final since he won the 2014 French Open.
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 win a record tenth French Open title, his first 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 (only after Bjorn 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 Muller.
On the 21th of August, he overtook the ATP No. 1 ranking from Andy Murray.
This made him the ATP player with the longest time span between first and most recent dates at No. 1 in the history of the ATP tour.