''I am not in condition to compete in the London Olympics and therefore will not travel as planned with the Spanish delegation to take part in the games,'' Nadal said. ''(This) is one of the saddest days of my career as one of my biggest ambitions, that of being Spain's flag bearer in the opening ceremony of the games in London, cannot be.''
It wasn't immediately known who would replace Nadal on Spain's tennis team or who would carry the flag at the opening ceremony in his place.
Nadal's absence leaves top-ranked Roger Federer of Switzerland and No. 2 Novak Djokovic of Serbia as the favorites, although Wimbledon runner-up Andy Murray of Britain will again likely have a wave of home support as he tries to reach the final at the All England Club for the second time in less than a month.
Murray lost to Federer in the Wimbledon final on July 8. The tennis gold medal match at the Olympics will take place on the same Centre Court on Aug. 5.
Both the men's and women's doubles champions are set to defend their Olympic titles in London, however. Federer and Switzerland teammate Stanislas Wawrinka are the men's defending champions, while American sisters Venus and Serena Williams won gold in the women's doubles in Beijing.