Novak Djokovic suffers defeat in men's doubles

Novak Djokovic has suffered an opening-round defeat for the second time in 24 hours after he and Nenad Zimonjic lost out in the men's doubles.

On Sunday night, Djokovic was surprisingly beaten in straight sets by Juan Martin del Potro, and his wait for an Olympic medal will be extended by a further four years if he does not receive a place in the mixed doubles.

Djokovic and Zimonjic were always outsiders to third seeds Bruno Soares and Marcelo Melo, and they were outplayed by the Brazilian pairing who conceded just one break of serve all match.

The home favourites sealed three of their own to run out 6-4 6-4 winners to set up a clash with Romania's Florin Mergea and Horia Tecau.