When Sharapova was inducted into the Tennis Hall of Fame on Saturday night, her former on-court antagonist provided the introduction. For many tennis watchers, Williams’s top-secret cameo was shocking but the moment capped a 180-degree turn in their once pointy rivalry.

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

Tennis legend Maria Sharapova joins TODAY to talk about her induction into the International Tennis Hall of Fame, calling it a celebration of the successful moments, the tough battles and the rivalries coming together.