Racing’s challenge flag
It is the final of the U.S. Open. Thousands cram into the seats at centre court to watch Novak Djokovic and Roger Federer compete in a tennis match for the ages. With the game on the line, Djokovic shoots a forehand winner past Federer. With a raise of his hand, Federer challenges the close call and fans wait with anxious anticipation for the digitally generated settlement to the argument.