French Open organisers defended their security arrangements after protesters, one letting off a flare and running on court, briefly interrupted the final between Rafa Nadal and fellow Spaniard David Ferrer on Sunday.
A police source said that 12 people were being questioned after the showpiece match was disrupted and protests broke out elsewhere at Roland Garros in Paris.
Security guards were called into action during the final when two bare-chested protesters stood up in one of the front rows behind the players' benches on court Philippe Chatrier at the end of the sixth game of the second set.
One protester, wearing a white face mask, let off a flare and ran onto the court towards Nadal.
He was brought down by a member of security staff before being dragged out with his accomplice, who did not get the chance to step onto the court.
Earlier four other protesters were evicted from the stadium by security while six were evicted from the neighbouring Court Suzanne Lenglen where Legends matches were taking place.
"Twelve people have tried to disrupt the match. They have been caught by the security staff of the tournament and been handed over to the police," a police source, who declined to be named, said.
"They are being questioned by the police."
Tournament director Gilbert Ysern told reporters: "This kind of thing is regrettable but it has been taken care of remarkably by our security staff.
"I apologised to the two players. At the time, you are scared but we were quickly reassured.
"These people are good-for-nothings."
Nadal's coach and uncle, Toni Nadal, told reporters he was not scared but runner-up Ferrer joked that his opponent had been affected.
"It's funny, Rafa was scared a little bit," a smiling Ferrer said.
"It's strange but I did not lose my focus."
Earlier, four protesters had been pulled out of the higher rows of the Philippe Chatrier stands by security.
They had displayed banners in both French and English saying 'Help! France tramples on children's rights'.
Six other protesters, also bare chested and brandishing flares, climbed to the top row of the neighbouring Court Suzanne Lenglen and unfurled a banner saying 'HOLLANDE DEMISSION' ('Hollande resignation') before being bundled out by security.
Last month, French president Francois Hollande signed into law a bill allowing same-sex marriage amid a series of large, and sometimes violent demonstrations.
The first same-sex marriage was celebrated in Montpellier on May 29.
This is not the first time the French Open final has been interrupted by a court invader. Four years ago, a fan tried to put a hat on Roger Federer's head during his victory over Sweden's Robin Soderling.
Image: A security personnel (right) attempts to stop a flare-wielding protester against same-sex marriage, on the court during the men's singles final between Rafael Nadal and David Ferrer on Sunday
Photograph: Philippe Wojazer/Reuters