Charlie Gard's parents are preparing to return to court for a hearing at which the terminally-ill baby's future could be decided.
Mr Justice Francis is set to oversee the latest stage of Chris Gard and Connie Yates's five-month legal fight over treatment at a hearing in the Family Division of the High Court in London.
The judge had been scheduled to analyse what the couple said was fresh evidence at a two-day trial starting at 10am on Monday.
He said he aimed to make a decision on Tuesday and questioned whether a two-day hearing would be long enough.
But the hearing has now been re-listed and is scheduled to start at 2pm on Monday. Lawyers have given no explanation for the scheduling change.
On Friday a barrister representing Great Ormond Street Hospital doctors caring for the 11-month-old boy told Mr Gard and Ms Yates that a report on the latest scan made for "sad reading".
Ms Yates burst into tears when Katie Gollop QC broke the news at a preliminary hearing in the Family Division of the High Court.
Mr Justice Francis asked Ms Gollop not to reveal full details of the report - the judge indicated that Charlie's parents should be given time to consider it privately.
Last week the American specialist, Michio Hirano, a professor of neurology at Columbia University Medical Centre in New York, travelled to London to examine Charlie for the first time and discuss the case with Great Ormond Street doctors.
Lawyers told the judge that they would analyse reports from the gathering over the weekend.
Mr Gard and Ms Yates have asked judges to rule that Charlie, who suffers from a rare genetic condition and has brain damage, should be allowed to undergo a therapy trial in New York.
Doctors at Great Ormond Street say the therapy is experimental and will not help.
They say life- support treatment should stop.
Charlie's parents, who are in their 30s and come from Bedfont, west London, have already lost battles in the High Court, Court of Appeal and Supreme Court in London.
They have also failed to persuade European Court of Human Rights judges to intervene.
But the couple say there is new evidence and asked Mr Justice Francis, who in April ruled in favour of Great Ormond Street and said Charlie should be allowed to die with dignity, to change his mind.
Mr Justice Francis has told the couple that he will not re-run the case but will consider any ''new material''.
:: Great Ormond Street chairwoman Mary MacLeod said doctors and nurses have been subjected to abuse in the street and received thousands of threatening messages in recent weeks. She said the hospital is in close contact with police.