Prestyn Barnette wasn't interested in asking for toys this year.

What the four-year-old South Carolina boy really wanted was a Christmas miracle.

In a photo that is touching hearts the world over, Prestyn asked the Santa in his local mall at the weekend to pray with him for a sick baby that is fighting for life.

And the two did just that.

What is making the moment even more poignant is the fact Prestyn has never met the baby he is praying for.

According to his aunt, Lauren Sharpe, Prestyn has been enamored with the story of Knox Stine, a two-month-old who is fighting for his life in a Las Vegas hospital.

Prestyn heard the story while spending time with his grandmother, who is part of a prayer group that heard of Knox's condition on Facebook.

Baby Knox is being cared for at Sunrise Children's Hospital in Las Vegas - across the country from where Prestyn lives in Columbia, South Carolina - after he was found unresponsive by his father on November 30.

'We got up there and Santa asked him what he wanted for Christmas,' Sharpe told ABC News.

'He asked for a Lionel train set and to pray for a miracle for Baby Knox.'

Now Prestyn has unwittingly helped bring in a lot for prayers for the little boy.

'The more people that see his picture and baby Knox's story, the more people there are to pray for a miracle!' Sharpe added.

Despite the photo going viral and being seen by people all over, none have been more touched than Knox's mother, Mindi Stine.

'I thought it was beautiful,' she told ABC.

'I thought the boy was precious and I think it's so sweet. It spoke to my heart.

'Even though I am experiencing pain that is unbelievable, that brought joy to me.'

After Knox was found blue and limp by his father in the family's Arizona home last month, he was transferred to Las Vegas for treatment.

Knox was declared brain dead, however a second examination doctors found blood flow in his lower brain.

Knox will now undergo a tracheostomy to help him breath.

His family continue to hold out hope, and have set up a GoFundMe account to assist with their ongoing medical bills.