Nadal was named Spanish male athlete of the year for 2017 in Mundo Deportivo's Grand Gala on Monday (5 February) after a remarkable year that saw him win six titles.
In addition to reaching the summit of the ATP tennis rankings for the first time since 2013, Nadal won a record 10th French Open title as well as a third US Open crown.
The Spaniard's 2018, though, did not get off to the best start after he had to pull out of his Australian Open quarter-final clash with Marin Cilic due to a hip issue.
However, he is looking to emulate his performances from last year and remain world number one. The two players that stand in his way are Federer and Djokovic, who the 31-year-old called his biggest adversaries, having suffered a combined 41 losses to the duo in 88 career meetings.
"I want to keep winning," Nadal said at Mundo Deportivo's Grand Gala via Express. "But also my rivals, my worst rival, all those who beat me make me nervous.
"I think my two biggest rivals were Federer and Djokovic, with which we have competed for the most important things throughout our career, a desire for 2018."
Injuries have been a problem for Nadal throughout his career, and after having had to pull out of the ATP Finals in London back in November 2017, the Manacor native suffered another setback in Melbourne in January this year. The eventual winner in Federer now is just 155 points behind him.
However, he expects to be back for the Mexican Open in Acapulco as he spoke about how not having a clean bill of health makes everything complicated.
"Health, without health, everything else is more complicated, not only regarding sports injuries, but in general," Nadal added.
The Mexican Open will take place from 26 February to 3 March, with Nadal looking to do one better this year, having lost to Sam Querrey in last year's final.