linguistic:paraphrasing, linguistic:translation
2021: 12th Barcelona Open and 10th Italian Open titles, and injury-shortened season

At the 2021 Australian Open, Nadal lost in the quarterfinals to world No. 5 Stefanos Tsitsipas, despite being two sets to love up. This marked only the second time Nadal had lost a Grand Slam match after being two sets up. Nadal next played at the Monte Carlo Masters and defeated Federico Delbonis and Grigor Dimitrov in straight sets to reach the quarterfinals, where he lost to Andrey Rublev in three sets. On 25 April, Nadal won a record-extending twelfth Barcelona Open trophy with a three-set victory over Stefanos Tsitsipas in the final, saving a championship point in the third set. At 3 hours and 38 minutes, this was the longest best-of-three-set ATP Tour final since statistics started being tracked in 1991. He followed up in May by making the quarterfinals at the Madrid Open and winning his record-extending tenth Italian Open title. In the latter, he saved two match points against Denis Shapovalov and defeated Novak Djokovic in the final.

At the French Open, Nadal entered as the heavy favorite seeking to become the first man to win 21 majors. He reached the semi-finals after wins over Jannik Sinner and Diego Schwartzman, where he encountered Novak Djokovic in a rematch of the previous year's final. There, Nadal was upset by eventual champion Djokovic in four sets, in only his third-ever loss at the French Open and his first loss in the semi-finals. Following his loss, Nadal withdrew from both Wimbledon and the Olympics, citing schedule reasons.

Nadal returned to action at the 2021 Citi Open, revealing that his recent withdrawals were actually due to a recurring left foot injury that returned at the 2021 French Open. He defeated home favorite Jack Sock in a tight 3 set match before being upset by 50th ranked Lloyd Harris in the 3rd round. He was then set to defend his title at the National Bank Open, but withdrew from the tournament before his first match, citing the same foot injury. He also withdrew from the Cincinnati Open.

On 20 August 2021, just 10 days out from the US Open, Nadal announced that would be ending his 2021 season due to the left foot issue that had been troubling him for most of the year. Therefore, his ranking fell to No.6, due to his injury.

Nadal returned to the court on 17 December 2021, in an exhibition match at the Mubadala World Tennis Championship in Abu Dhabi. Receiving a bye in the quarterfinals, Nadal lost to Andy Murray in the semi-finals in straight sets. In the third place play-off, he lost to Denis Shapovalov in three sets.