Federer, Djokovic set for first grass match

Novak Djokovic and Roger Federer have met 26 times, but Friday's potentially epic Wimbledon semifinal will be a first clash on grass in their rollercoaster, six-year rivalry.

Defending champion Djokovic has won the pair's past three meetings, in straight sets on clay this year in Rome and in the semifinals of the French Open. Those wins followed a morale-sapping semifinal loss for Federer at the US Open where the Serb, for the second successive year, saved match points before driving another dagger into the great Swiss.

Both men go into Friday's clash having racked up impressive numbers.