Former world number one Rafael Nadal has conceded that his right knee is still causing him pain.

The Spaniard made his first competitive appearance on the tennis court since June 2011 last week in Chile and went on to reach the final of the VTR Open, before being beaten by Horacio Zeballos.

However, despite the defeat and discomfort, Nadal has admitted that he was pleased to have returned to action.

"A week ago we didn't know how the body would respond," he said. "[Now] at least I know we can compete at a certain level. I think that was a positive week. I will try to keep improving my physical sensations day by day, which is the most important thing because I don't feel that my tennis level is bad. I need more time on court.

"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."

Nadal is now expected to compete in Brazil over the next few days.