Shanghai - Roger Federer will have to shrug off a bizarre death threat as he returns to action at the Shanghai Masters from Sunday to combat Novak Djokovic's attempt on his world number one crown.
Security precautions are in place for the Swiss player and his family in the teeming Chinese city, after a unknown blogger made the outlandish threat to "assassinate" the 17-time Grand Slam champion.
"On October 6, I plan to assassinate Federer for the purpose of tennis extermination," read the message, posted under the name 'Blue Cat Polytheistic Religion Founder 07' on baidu.com.
The user also posted a doctored image showing a decapitated Federer on his knees on a tennis court, with an axe-wielding executioner posing next to him.
While the credibility of the threat was unknown, organisers were taking no chances.
"We are fully aware of the comments that have been made and we take all such issues seriously," a tournament official said.
The incident has provided an unwelcome distraction ahead of the Shanghai Masters, where Federer and Djokovic will take centre-stage along with Britain's defending champion Andy Murray, fresh from his US Open success.
Federer, 31, missed the 2011 Shanghai Masters but has an enviable record at the magnolia-shaped Qi Zhong Stadium, winning two of his six season-ending showpiece titles there before the event shifted to London.
"It will be fantastic to return to Shanghai," Federer said. "I love the city and especially the fans. I've enjoyed great success at the tournament, dating back to the Tennis Masters Cups."
As the gruelling season enters its final few weeks, the Swiss has 11 805 points in the rolling 12-month rankings with Djokovic in second place on 10 470. A total of 1 000 points are on offer to the winner in Shanghai.
But crucially the Serb has fewer points to defend for the rest of the season, and his eye is firmly on supplanting Federer by the end of the year.
"That's one of the goals. Of course I want to be No 1 of the world again. It's an ambition. It's possible by the end of the year," said Djokovic, who also missed last year's event, through injury.
Meanwhile Murray, 25, defends his title still on a high from his historic win over Djokovic in the US Open final, which made him Britain's first men's singles Grand Slam champion since the 1930s.
But the Scot downplayed suggestions he has been the best player of a vintage season with four different Slam winners, after Djokovic won the Australian Open, Rafael Nadal took out the French Open and Federer triumphed at Wimbledon.
"There are four Slams, but there are also many other tournaments to get to number one in the world," he said.
"I think if you're number one you deserve to be the player of the year. I would say Novak or Roger would be the best players this year."
Third-ranked Murray, who beat Spain's David Ferrer in the Shanghai final last year, is currently more than 2,000 points adrift of Djokovic and looks unlikely to reach number one for the first time in his career.
Other big names in the Shanghai mix include powerful Frenchman Jo-Wilfried Tsonga, Tomas Berdych of the Czech Republic and Argentina's former US Open champion Juan Martin del Potro.
Eleven-time Grand Slam-winner Nadal remains out with a knee injury and is reportedly targeting a return at next month's ATP World Tour Finals and the Davis Cup final.