This is any parent's worst nightmare and we're sending so many prayers.

Michael Buble and wife Luisana Lopilato's 3-year-old son has been diagnosed with cancer, the singer shared in a heartbreaking Facebook post today.

"We are devastated about the recent cancer diagnosis of our oldest son Noah who is currently undergoing treatment in the U.S. We have always been very vocal about the importance of family and the love we have for our children," the couple wrote in a statement.

The crooner, 41, and Lopilato, 29, are also parents to son Elias, 9 months.

"Luisana and I have put our careers on hold in order to devote all our time and attention to helping Noah get well. At this difficult time, we ask only for your prayers and respect for our privacy. We have a long journey in front of us and hope that with the support of family, friends and fans around the world, we will win this battle, God willing," they added.

We can't imagine a more difficult thing to go through.