Rafael Nadal has played through constant pain since 2005, says Toni Nadal

Rafael Nadal's former coach Toni Nadal has revealed the World No 2 has been playing through constant pain since 2005. The Spaniard's uncle also revealed the tennis star would rely on painkillers "a lot of times" to ease the pain.

The 31-year-old made his mark in the early 2000s and won his first Grand Slam title in 2005 at the Roland Garros. He went on to win the tournament nine more times, which is the record for the most number of titles in a single Grand Slam event.

Toni said the problem in Rafael's foot was detected in 2005 and the then-teenager was told he would not be able to continue playing professional tennis. However, the 10-time Grand Slam winner continued with the sport and his former coach said the "congenital injury" forced Rafael not to complete training sessions on multiple occasions.

"In 2005 they told us they detected a problem in Rafa's foot — a congenital injury — and the specialist we went to told us that Rafael's career was pretty much finished," Toni Nadal was quoted as saying by ABC.

"From the end of 2005 on, Rafael had to constantly live in pain. From that time on we couldn't finish training sessions a lot of the time."

Rafael started using insoles to get some relief from the foot injury, but it led to other problems. Toni revealed that use of the insoles led to pain in his knee. The former World No 1's career was marred by knee injuries, which forced him to miss or withdraw from a lot of major tournaments.

"A lot of times, almost always, he would have to take a painkiller because the pain would get worse and worse as matches went on," Toni explained.

"Because of some insoles that he started using, which solved his foot problem, he started having problems in his knee, back and other parts of his body.

"I remember in 2013 he told me once ... after his year had been really good ... he told me 'sometimes I wish I'd win less and have less pain'."

Toni has been alongside Rafael because the former was the tennis star's coach until the end of the last season. The 16-time Grand Slam winner's uncle decided to step down as his nephew's coach in order to focus on the tennis star's academy in Spain.

A hip injury forced Rafael Nadal to withdraw from the 2018 Australian Open quarter-final in January. After he spent over a month on the sidelines, a recurrence of the same injury saw the Spaniard missing the 2018 Mexican Open.