After seven months away treating a left knee injury, Rafael Nadal has left many questions unanswered in his comeback tournament.

Nadal lost both the singles and doubles finals in the space of a few hours Sunday at the VTR Open in Chile. Horacio Zeballos beat Nadal in three sets for the first title of his career.

Nadal says the loss was a reminder of what he already knew. He realizes that returning to challenge the other three in tennis' top four — Novak Djokovic, Roger Federer and Andy Murray — will be slow and gritty.