Charlie Gard's parents have said they are hopeful ahead of a court hearing in their latest bid to see him treated with an experimental therapy.
The terminally ill 11-month-old, who is on life support at Great Ormond Street Hospital (GOSH), remains at the centre of a legal battle which has gained interest across the globe.
His mother Connie Yates and father Chris Gard said they are determined to continue their fight for their son to have nucleoside therapy, which is available abroad.
The couple handed a 350,000-signature petition to GOSH on Sunday, signed by people around the world.
It called for the family to be allowed to travel to receive the experimental treatment, something currently blocked by a High Court ruling.
Flanked by a small group of supporters, some of whom had flown in from the US, they told reporters they had nothing to lose by pushing ahead with their fight.
Ms Yates said: "He's our son, he's our flesh and blood. We feel that it should be our right as parents to decide to give him a chance at life."
The 31-year-old added: "There is nothing to lose, he deserves a chance."
Their previous legal attempts have failed as judges in the High Court, Court of Appeal and Supreme Court in London ruled in favour of GOSH doctors, while the European Court of Human Rights declined to hear the couple's appeal.
The case will come back to the High Court on Monday afternoon to hear fresh arguments following claims of "new information" from researchers at the Vatican's children's hospital.
Charlie inherited the faulty RRM2B gene from his parents, affecting the cells responsible for energy production and respiration and leaving him unable to move or breathe without a ventilator.
GOSH describes experimental nucleoside therapies as "unjustified" and the treatment is not a cure.
The hospital's decision to go back into the courtroom came after two international healthcare facilities and their researchers contacted them to say they have "fresh evidence about their proposed experimental treatment".
Charlie's parents, who said they reluctantly left their son's bedside at the weekend because they wanted to thank supporters for backing their cause, said they feel stressed but hopeful.
They told the Press Association: "The whole world knows about us and about Charlie and our fight. There's a lot of pressure on it. It's hard work but we have hope so that keeps us strong. Charlie keeps us strong.
"Until you're in this situation, you don't understand the power of hope."
While Ms Yates and Mr Gard said they have been boosted by support from US President Donald Trump and the Vatican, a leading expert has described interventions from high-profile figures as "unhelpful".
Professor Neena Modi, president of the Royal College of Paediatrics and Child Health said in an open letter that Charlie's situation is "heartbreaking" for his parents, and "difficult" for others including medical staff, but added that even well-meaning interventions from outsiders can be unhelpful.
Charlie's parents, from Bedfont, west London, spoke out on Sunday, saying they wanted to respond to what they described as "myths" in their son's case and criticised "misinformation".
Despite GOSH saying he can "probably" experience pain but cannot react, the couple maintained they know their son is not suffering.
The treatment - which Charlie's parents said they believe has an "up to 10% chance of working" - is "potentially painful" and "very unlikely" to improve his condition, the hospital said.
Mr Gard, 33, said that while Charlie's brain is affected there is no evidence of "catastrophic brain damage", but doctors treating him said they believe his brain damage is "severe and irreversible".
The parents said they want to be trusted to act in his best interests, with Mr Gard adding they would stop the treatment if they believed it was harming their son.
He said: "If we won the court case and we got to America, and then within the first week of treatment he started suffering and he was in pain, we would let him go.
"This isn't about us. This is about Charlie and giving him the chance he needs."
Charlie's case will be heard by Mr Justice Francis at 2pm, according to a High Court listing.
The interest of the Pope and US President Donald Trump in Charlie's case has "saved his life so far", his mother has said.
Ms Yates told BBC Radio 4's Today programme: "Yeah, they have saved his life so far.
"It turned it into an international issue. There are a lot of people that are outraged by what is going on. We have got new evidence now so I hope the judge changes his mind."
She said that "sometimes parents are right in what they think" and it is not simply that they do not want to switch off life support.
She said the family now have seven specialist doctors - two from the US, two from Italy, one from England and two from Spain - who are supporting them.
She added: "We expect that structural damage is irreversible but I have yet to see something which tells me my son has irreversible structural brain damage."