On April 30, 1993, Gunther Parche ran down from the middle of the stands and stabbed Monica Seles between the shoulder blades with a seven-inch boning knife while she sat on the bench on a changeover during her quarterfinal match against Magdalena Maleeva in Hamburg.

“We’ve had threats to Monica before, and to other players as well,” said Gerard Smith, Executive Director of the Women’s Tennis Association then. “But this is bizarre. You can’t imagine someone who would take a sport to such an absurd level.”

The good news is security has indeed tightened since then. As Roger Federer, Maria Sharapova and Serena Williams transcended the sport to become celebrity icons, a more robust system of background checks, bodyguards and watch lists developed. And for all the concerns about how social media can put an athlete at risk, it also has allowed players and security personnel to identify potential threats and red flag individuals.