Rafael Nadal worried over Olympic fitness

Rafael Nadal has admitted that he is worried over his fitness for this summer's London Olympics.

The Spanish world number two is currently suffering with a knee problem following his shock exit to Lukas Rosol at Wimbledon.

"I am working as hard as I can and hopefully I will be at 100%," said the 26-year-old.

"I am the one who is most worried. I hope that things improve and my intention is to arrive in London well prepared and recuperated. It is for this that I work every day."

Nadal has been chosen to carry the Spanish flag during the opening ceremony of the Games.