At the tender age of 16, Yugoslavian-born Monica Seles announced her arrival at the Grand Slam stage when she won her the French Open in 1990, kicking off a rivalry with Steffi Graf that would nearly cost Seles her young life.

When the 1993 Citizenship Cup in Hamburg, Germany came around in April, No. 1 seed Seles was on top of the women’s game, having won her eighth Grand Slam singles crown a few months earlier at the 1993 Australian Open, which saw her defeat then-Germany’s top No. 1 player Steffi Graf in the final.

Then, something horrible happened during the changeover in Seles’s quarterfinal match in Hamburg. An obsessed fan of Graff, Gunter Parche, sent shock waves through the tennis community after he stabbed Seles in the back with a knife. His reason was that he wanted to help his German compatriot reclaim the No. 1 position. Graf did indeed return to the top that year.

Seles, however, returned to the tour, only winning one more major as she had a tough time putting the horrifying incident behind her.