Today's French Open winner Roger Federer was stunned when a man ran onto the Roland Garros tennis court in Paris and tried to place a red hat on his head.
Unphased by the on-court intruder, Federer defeated surprise finalist Robin Soderling of Sweden 6-1, 7-6 (1), 6-4 on to complete a career Grand Slam and win his 14th major title.
"It's maybe my greatest victory, or certainly the one that removes the most pressure off my shoulders," Federer said. "I think that now and until the end of my career, I can really play with my mind at peace, and no longer hear that I've never won Roland Garros."
The Swiss tennis star pushed the intruder aside as the man danced in front of the crowds waving a Barcelona soccer team flag.
The man, who claimed to be a Federer fan, eluded attempts by security guards to subdue him and jumped over the net. A security guard from Soderling's side of the court then ran out and tackled him, and three other guards carried the man off the court.
Intrusions have happened at Grand Slam finals before, at Roland Garros and elsewhere, but what made this episode frightening was that the man actually touched Federer.
Police are holding the intruder for questioning and say he could be charged with illegally entering a sports stadium.
After the man was taken away, a security guard approached Federer to check if he was all right.
The breach of security was reminiscent of the 1993 stabbing of Yugoslavia-born tennis star Monica Seles in full view of a 6,000-strong crowd in Germany.
The No. 1 woman's tennis player at the time, Seles was stabbed in the back with a five-inch knife during a quarter-final match in Hamburg during a rest break in the match against Bulgarian player Maggie Maleeva.
At first, authorities speculated that the attack was politically motivated because of Seles' Serbian roots and previous death threats during the Yugoslav conflict.
Eventually, 39-year-old Gunter Parche, an unemployed lathe operator, was arrested. At the time, he was described as a loner who was obsessed with German tennis star Steffi Graf. He was deemed mentally ill and sentenced to two years in jail.
Doctors rushed the 19-year-old star was rushed to hospital with a half-inch wound in her upper back. The injuries were non-life threatening.
Seles was never able to make a career comeback and said publicly she would never feel safe again on the court.
Later, at the 2001 Hopman Cup in Perth, Australia, Seles was spooked when she was tapped on the back and asked for an autograph while sitting court side in the stands.
During a 2003 news conference in Miami, Seles said, "I don't feel it's sufficient, in a lot of ways. Our accessibility to people, [they can] get to us on site, in matches, after matches, and not just me. I think it's any of the high-profile players."
Seles played her last professional match the same year at the French Open and officially retired in February 2008.
Serena Williams Hires Bodyguard
A decade after the Seles' 1993 stabbing, tennis star Serena Williams hired a bodyguard to protect her because of persistent threats from a German stalker. He was apprehended in 2003 at Wimbledon in England and in New York.
In 2002, top player Martina Hingis testified against a stalker who was sentenced to two years in a Florida jail.
Security breaches don't just happen on the tennis court.
Major League Baseball fans have watched intruders come onto the field or seen players struck with objects thrown from the stands. Just this spring, a naked man ran onto the new Citi Field during a New York Mets game.
In 2003, at Chicago's U.S. Cellular Field, a fan tried to tackle umpire Laz Diaz, a former Marine. Earlier, at the same venue between the same teams -- the White Sox and Royals -- a father and son attacked Kansas City Royals' first-base coach Tom Gamboa.
In Oakland, Calif., that same year, a 24-year-old fan allegedly hit right fielder Carl Everett of the Texas Rangers in the back of the head, throwing a cell phone at him from the second deck. Everett was not hurt, but the man was charged with assault with a deadly weapon.
In another incident, Padre third baseman Sean Burroughs was hit from the stands in Chicago with a cell phone.
ABC's information specialist Brad Martin contributed to this report.