David Beckham felt "threatened" and "frightened for the safety of his family" when an alleged stalker went to his daughter's school, a court heard.
Sharon Bell, of Watford, was said to be under the delusional belief that she had a relationship with the ex-England footballer, magistrates heard.
The defendant, 58, claimed Beckham and his wife stole her eggs and their 10-year-old daughter Harper was her child.
Ms Bell denies stalking and is due to stand trial in July.
She allegedly sent a series of letters to the Beckhams' homes in Oxfordshire and London before attending the addresses in July and September.
Westminster Magistrates' Court heard that she also turned up at Harper's primary school in a bid to speak to her, and was there when ex-Spice Girl Victoria Beckham, 48, arrived to collect her daughter.
'Absolutely bizarre assertion'
Prosecutor Arizuna Asante said 47-year-old Beckham, who played at club level for Manchester United, Real Madrid, LA Galaxy, Paris St Germain and AC Milan, had felt "threatened".
"He felt frightened for the safety of his family, and he believed this behaviour was targeted and intimidating," she said.
"He says he does not know the defendant and she is not the mother of his children."
Ms Bell, of Boundary Way in the Hertfordshire town, did not attend the hearing, which was told she was currently in hospital, where she had been sectioned.
Her lawyer, Lisa Wilson, said that if her client was found by the court to be unfit to stand trial, she would want the Beckhams, who will be on holiday at the time of the hearing, to be called as witnesses so they could be questioned about her claims.
The court heard that this would include putting the suggestion to Victoria Beckham, who has four children with her husband, "that she conspired with David Beckham to steal the eggs of Sharon Bell".
The judge extended a civil interim stalking protection order until the end of the proceedings, which he indicated were likely to go down the "psychiatric route", resulting in a hospital order.