Tennis:Rafa Nadal's worst defeat on a claycourt for nine years offered ammunition to the naysayers but the Spaniard says his recovery from knee injury should be judged over time.

The seven-times French Open champion’s narrow loss to Argentine world number 73 Horacio Zeballos in Vina del Mar on Sunday was rightly regarded as a shock as Nadal’s defeats on clay over the past eight years can be counted on two hands.

Even those rare reversals have come against players of the calibre of Roger Federer and, most notably, Novak Djokovic in 2011 and the last time he lost to a player outside the world’s top 20 on clay was five years ago in Rome when former world number one Juan Carlos Ferrero got the upper hand.

The 26-year-old Nadal admitted the knee was still causing him pain. “The knee is still bothering me, but you have to face adversity with the best possible face and look forward to keep working and enjoy what I like the most, to play tennis,” he said.

“A week ago we didn’t know how the body would respond. At least now I know we can compete at a certain level. I think that was a positive week.”