After seven months away treating a torn and inflamed tendon in his left knee, Rafael Nadal left many questions unanswered in his comeback tournament.

Nadal lost both the singles and doubles finals in the space of a few hours on Sunday at the VTR Open in Chile. And Horacio Zeballos, whose three-set victory over Nadal in singles brought him the first title of his career, repeated what Nadal has been saying.

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