Security was beefed up on Friday as Roger Federer trained for the weekend start of the Shanghai Masters amid a death threat posted online.

The world number one, who arrived in China’s commercial capital this week with his family, was the target of the threatening posting last month.

The Swiss is playing the event for the first time since 2010.

The presumed threat came from an anonymous blogger on a local site and featured a photo-shopped image.

“On October 6, I plan to assassinate Federer for the purpose of tennis extermination,” read the message on posted by “Blue Cat Polytheistic Religion Founder 07.”

Chinese media said that protection for players has moved to a higher level at the Qi Zhong arena and the central Shanghai official tournament hotel.

“We hope that it was an oral threat only, and the fan won’t take substantive action,” said tournament official Yang Yibin “We must take it seriously. We have contacted the local police and we will upgrade the level of security for Roger. Meanwhile, we will also protect other players’ security.”

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