Eleven potential stalkers have been warned by police to stay away from Wimbledon over the next two weeks.
Police at the All England Club in south-west London did not provide details of which players were at risk from the "fixated individuals", but the Russian star Maria Sharapova and the American Williams sisters – Venus and Serena – are believed to be the subjects of the greatest number of fanatical fans.
A man believed to be stalking Sharapova was banned from the tournament in 2005.
Police wrote to the 11 potential trouble-makers and told them to stay away from the tournament, which began yesterday. Supt Pete Dobson said: "There are a number of individuals well known to the police, the All England Club and the tennis authorities. They have been written to and banned from entering the club."
In their annual briefing before the tournament, the police also revealed that a member of the family of one of the competitors – believed to be a young female player – has been issued with a restraining order by an American court which bars him from Wimbledon during the next two weeks.
Although many top-level players have had trouble with stalkers, the most famous incident happened in Germany in 1993. Monica Seles, then 19, had recently defeated Steffi Graf in the final of the Australian Open. During Seles's quarter-final match in Hamburg against Maggie Maleeva, a deranged Graf fan, Günter Parche, leant over the spectator barrier and stabbed her in the back. Parche was given a two-year suspended sentence, while Seles was out of action for two years.
Last night, a police source said of the potential Wimbledon stalkers: "Maria Sharapova does have some fixated individuals interested in her, as do Venus and Serena Williams. I would say the two sisters have had the most interest over the years. There is a mix of people from abroad and the UK who are known to us. There are no specific threats this year, although there have been in the past, several years ago."
All security personnel at the tournament have been issued with photographs of the potential stalkers. Up to 30 ticket touts have also been written to by the police, who are seeking to crack down on illegal activity at the event.
A dispersal zone – two kilometres by one kilometre and including the nearby Underground station of Southfields – has been set up. Groups of two or more people deemed to be behaving "antisocially" will be moved on, with those who refuse facing a possible three-month prison term or £2,000 fine.
The new rules take advantage of the Antisocial Behaviour Act 2003, but this is the first time it has been used at a sporting event. Supt Graeme Thomson said: "We are concerned about the high number of [ticket] touts coming down causing harassment, alarm and distress. Having big burly blokes coming up to you at the Tube station trying to sell you tickets that could be lost, stolen or potentially forgeries is anti-social."
Other security has also been tightened, with concrete blocks placed on the approaching roads. Although Wimbledon is not considered to be specifically at threat from a terrorist attack, Supt Dobson said the general terror threat was now considered to be severe. "This means we believe an attack is likely for the UK, but that doesn't mean that the championships is a target," he said.