Goncalo Amaral, 57, said early rulings by the judge in the case suggested her verdict may be 'favourable' to him.
Madeleine's parents Kate and Gerry, both 46, claim the ex-cop's controversial book about the then-three-year-old's disappearance in 2007 left them devastated.
In his book and a follow-up TV documentary Mr Amaral said he suspected the youngster had died in the family's holiday apartment in Praia da Luz and accused the couple of hiding the tragedy.
Kate spent 55 minutes detailing to the court in Portugal's capital Lisbon the distress she said his claims had caused.
But the couple's chances of pocketing a big pay-out appear to be dashed after the judge gave a crushing preliminary ruling.
Judge Maria Emilia Melo e Castro said she did not find the couple had been 'completely destroyed' from a 'moral, ethical and family point of view' as a result of the book.
She said it was not proven they would suffer 'permanent anguish, insomnia, lack of appetite and an indefinable fear'.
The judge said this psychological state existed before the publication of Mr Amaral's The Truth Of The Lie.
She said it was normal for the couple to be affected by the book and they would have 'felt badly' over allegations by Mr Amaral that they hid their daughter's body.
But she said it was not possible to determine what most people would have thought after reading Mr Amaral's theories.
The McCanns have claimed Mr Amaral's assertion their daughter is dead stopped people looking for her.
The judge said she was satisfied some facts in the book came from official Portuguese police files - though others did not.
She is due to give her final ruling next month.
Mr Amaral, who is now retired, told Portuguese TV her indications so far led him to believe he would win the case.
He said he wrote the book to defend the initial police probe into Madeleine's disappearance which he led for four months before being axed after accusing Brit detectives of siding with the McCanns.
The McCanns' lawyer Isabel Duarte was unavailable for comment on the judge's initial findings.
Scotland Yard detectives are conducting a £10m investigation in a bid to find out what happened to Madeleine.
They have cleared the McCanns of any involvement and suspect she was killed in a botched burglary.
