A rising British tennis star who fell ill, forcing her to withdraw from Wimbledon, could have caught an infection from dirty water, according to an expert in microbiology.
Police are investigating allegations that Gabriella Taylor, from Southampton, was targeted during last month's championships.
The 18-year-old spent four days in intensive care after becoming unwell and her mother, Milena Taylor, told the Daily Telegraph her daughter was "close to death".
Scotland Yard said police in the London Borough of Merton, which covers Wimbledon, were investigating an allegation of poisoning with the "intent to endanger life" or cause grievous bodily harm. No arrests have been made.
A spokesman said: "The allegation was received by officers on August 5, with the incident alleged to have taken place at an address in Wimbledon between July 1 and 10. The victim was taken ill on July 6.
"It is unknown where or when the poison was ingested.
"The victim, an 18-year-old woman, received hospital treatment and is still recovering."
Taylor contracted a strain of the bacteria leptospirosis, which is usually spread by animals and can in rare cases cause organ failure, her mother told the newspaper.
She said her daughter was staying "in a completely healthy environment" and it was "impossible" for her to have become ill.
"The bacteria the infection team found is so rare in Britain that we feel this could not have been an accident," she said.
"Her bags with her drinks in were often left unattended in the players' lounge and someone could have taken the opportunity to contaminate her drink."
But Professor Elizabeth Wellington, an environmental microbiologist at the University of Warwick, said that to grow and infect someone with the bacteria would require a high level of expertise and is highly unlikely to be spread through spiking someone's drink.
She said: "It's a bit laughable ... if she has the disease then it's a case of bad luck, she has most likely become infected by water."
Prof Wellington said the bug was normally carried in the urine of rats and dogs and most people who caught it worked or were exposed to dirty water in canals or at sewage works.
A Public Health England spokesman said government figures showed there were 71 confirmed cases in England and Wales in 2015 and 76 during the previous year.
Prof Wellington added: "Spiking a drink is not going to work; it has to go through a wound, and in order to deliberately infect her, she would have to have an open wound and they would have had to get it in there - that's the unbelievable part.
"It is much more likely she has got it from natural sources rather than biological espionage."