Novak Djokovic & The Williams Sisters Play Tennis for Charity

Novak Djokovic throws a tennis ball up and down as he gets ready to play at the 2014 All-Star Charity Event at the Ritz Carlton at Cliff Drysdale Tennis Center on Tuesday (March 18) in Key Biscayne, Fla.

The 26-year-old world tennis pro was joined at the event by Venus and Serena Williams, as well as fellow Serbian tennis player Ana Ivanovic.

The event went to benefit First Serve Miami, which helps economically and socially challenged youth learn tennis.

“Ummm how could I forget?? Captain America came out this Friday!!!!???” Serena tweeted earlier this week – unfortunately for Serena, the new flick, Captain America: The Winter Soldier, is not out in theaters until April 4.

25+ pictures inside of all the tennis pros at the 2014 All-Star Charity Event…