The chilling message on a Federer fan website under the name of 'Blue Cat Polytheistic Religion Founder O7 had read . Security stepped up at Shanghai Masters in China . Top seed Roger Federer aware of online death threat . Federer makes public retirement announcement despite threats . Bidding to protect world ranking from Novak Djokovic .
Security stepped up at Shanghai Masters in China . Top seed Roger Federer aware of online death threat . Federer makes public retirement announcement despite threats . Bidding to protect world ranking from Novak Djokovic .