An online commenter posted a death threat against Roger Federer prior to the start of the Shanghai Masters. (Eugene Hoshiko/AP)

Memo to the internet: Words matter. So choose them wisely.

The tennis fan who posted an online death threat against Roger Federer last week has reportedly contacted the tournament in Shanghai to offer an apology. The fan, who posted on the popular Chinese site Baidu.com under the handle "Blue Cat Polytheism Founder 07" says he got caught up in the heat of a message board debate and said something he didn't mean. (Read the initial report in Italian here.)

"I’m terribly sorry," the poster said. "I was arguing with Federer fans and then I wrote something stupid … I hope that the organizers can understand me, forgive me, and if possible send my apologies to Federer and his family.”

The incident has been an unwelcome distraction for Federer, who learned of the threat 11 days ago but decided to play in Shanghai anyway. He arrived late last week without his family, with Mirka and the kids opting to stay home not because of the security threat but because the trip was organized in haste.

“Obviously maybe it’s a little bit of a distraction, there’s no doubt about it. But you have to be aware of what’s happening around you,” Federer said. “But that is the case anyway anywhere I go today with my fame and all that stuff.”

“So then obviously it came out in the press. That’s when things changed. It became much more public, which I’m a bit disappointed about, that it did come out in the press. It was something just very small on a website, nothing clear and concrete, people just debating. That it makes that big news is a bit surprising to me.”