How far should security go at sporting events?

— -- PARIS -- Once, when the Minnesota Twins were playing the Seattle Mariners in the Kingdome, a fan climbed over the fence onto the field near the left-field line. He wandered slowly and made it all the way to center fielder Kirby Puckett and asked Puck to sign the bill of his cap. The fan then walked back to the stands, climbed back over the fence and sat down in his seat. And he did it all without a single security guard attempting to stop him.

I was reminded of this Sunday when a fan ran onto Court Philippe Chatrier and tried to get a photo with tennis legend  Roger Federer after his straight-sets victory against Alejandro Falla. Federer was not happy about the incident. After all, a couple of fans also wandered onto a court where he was practicing Saturday. That doesn't help make a player feel safe.

Perhaps Federer's scariest incident came six years ago, when a fan stormed the court during the French Open, waved a flag and then tried to put a scarf on Federer's head.

"When people jump on the tennis court or the soccer field, it feels like the security must be tougher," Falla said. "Lately, nothing serious has happened to a player or an athlete, but one day something bad can happen. Like what happened to Monica Seles. You never know what the crazy people are going to jump on the court."

These things happen in sports. Protesters briefly interrupted the 2015 Australian Open final between Novak Djokovic and Andy Murray, and others did so here during the 2013 final between Rafael Nadal and David Ferrer.

Those were political protests, but like Sunday, usually the fan is either drunk or just plain stupid. Usually, nothing bad happens much beyond those two fans permanently ruining Hank Aaron's 715th home run video by circling the bases with him.

The security guards normally chase down the fans, remove them from the field (players told me in the past that they saw security officers rough up a culprit pretty good) and sometimes arrest them.

That was the case Sunday. The fan, who did not try to hurt Federer in any way, was quickly escorted from the court.

Ernests Gulbis said he wasn't too concerned about player safety: "If it's somebody big, I might run, but if it's somebody small I might stay." There are the rare occasions when something very bad does happen. Seles was infamously knifed in the back by a fan in 1993. She missed two years recovering and never quite returned to her old form. Two drunk fans attacked first base coach Tom Gamboa at Comiskey Park in 2002, punching him several times before security guards stopped them.