The knife attack on Monica Seles, which took place in Hamburg 20 years ago on Tuesday, not only dictated security at sports events over the last two decades, but changed the victim's life forever.
A similar attack must rank as every sports stars' worst nightmare and any harmless fan, waiting for hours simply for their idols' autograph, is now viewed as a potential threat by security staff.
French Open champion Maria Sharapova, who won her 20th consecutive clay-court match when she defended her Stuttgart WTA title on Sunday, is renown for having scores of bodyguards in the wings when she steps on court.
"It's not something I worry about, the security guys would be pretty quickly onto it if there was a problem," she said on the subject.
But Seles is the first to admit the attack robbed her of her self confidence.
She had finished both 1991 and 1992 as the world's top ranked female player and in 1990, aged just 16, she had become the youngest-ever French Open champion.
On April 30, 1993, the tennis world was at her feet.
Having won her eighth Grand Slam title at the Australian Open earlier that year, the Yugoslav (of Serbian origin) was still only 19 when she played her quarter-final at Hamburg's Rothenbaum in the day's last match.
Having won the first set against Bulgaria's Magdalena Maleeva, Seles was resting during a break in play when Guenter Parche, a 38-year-old unemployed tool maker, plunged a 23cm-long knife into her back.
Her attacker had waited four days for his chance.
His motive was that as an ardent admirer of Steffi Graf, he had been irritated that Seles had usurped the German in the world rankings.
After his arrest, he was found to be carrying 1000 deutschemarks (511 euros) and had a ticket to fly to Italy where Seles was registered to play at the Rome tournament the following week.
He told Hamburg police he had been planning the attack for weeks but only wanted to harm Seles, not kill her.
At his trial, Parche's lawyer said his client lived in a fantasy world and his interest in Graf had reached an unhealthy level, fuelling his hatred of Seles.
Experts confirmed Parche had a personality disorder and the judge ruled it was attempted assault, not murder, giving him a two-year suspended sentence.
Due to the light sentence, Seles has never set foot on German soil again.
"Germany is the country where that man attacked me from behind, yet was not sufficiently punished," she said later in a television interview.
"I cannot understand why this man did not have to pay for his crime."
Two factors saved Seles from further harm.
At the moment of her attack, she was bending forward to get up from her seat, sparing her the full length of the blade, which missed her spine by five centimetres.
A security guard then wrestled Parche to the ground to prevent a second stabbing, holding him in a headlock, while others rushed to help Seles.
"I didn't know what exactly had happened," Seles recalled.
"Suddenly I remembered it was hard to breathe and I felt a terrible pain in my back."
Parache was arrested and taken away in handcuffs by police, while a distraught Seles was taken to hospital.
Incredibly, the tournament was not cancelled and Graf, ironically, went on to beat Spain's Arantxa Sanchez Vicario in the final.
A million marks (511,291 euros) had been spent on security for the Rothenbaum tournament and Seles had employed several security guards to protect her.
She lapsed into depression after her attack and her weight shot up by 30kg due to binge eating.
She made her comeback in July 1995 in Atlantic City against Martina Navratilova and eventually won the Australian Open for the fourth time in 1996.
But she never recovered the form she has showed from before her attack and eventually retired in February 2008.
Having won nine Grand Slams before the attack, she would win only one more in her career.
Having suffered several strokes, Parche is now incapacitated in a nursing home in Nordhausen, Thuringia, but Seles said the scars of her attack are both physical and mental.
"I was stabbed on court, in front of thousands of people," she wrote in her autobiography.
"It is not possible to talk about distancing yourself from that. It changed my career and irrevocably damaged my soul.
"A split second made me a different person."