Hall of Famers Martina Navratilova, Jim Courier, Stan Smith and Andy Roddick were among those in the crowd, wearing their blue Hall of Fame blazers. Sharapova and the Bryan brothers also received a cast tennis racket that is the hall’s newest offering to inductees.

Williams' surprise appearance to induct Sharapova was "months in the making" and required the code name of another female icon.

Maria Sharapova was inducted into the International Tennis Hall of Fame on Aug. 23 — with a little help, and a touching speech, from friend and former on-court rival Serena Williams.