After he was upset by Horacio Zeballos in the final of Vina del Mar, Rafael Nadal says his legs aren’t strong enough yet. Nadal returned to play last week after taking seven months off due to knee trouble.

“I’m lacking reaction speed, energy and leg strength I need in order to give my balls more depth, things that I have had throughout my career,” he told reporters. “I played with everything I had and today I had nothing,” he said.  
Nadal, who will play Sao Paolo this week, also acknowledged that, “there are days when the knee is better, some days are worse, and that affects my performance.”  
The Spaniard did say there are reasons to be hopeful, as a few weeks ago, “we did not know how the body would respond, or the knee in general. At least now I know we can compete at a certain level. I think it was a positive week.”