The Essex teenager wowed the Black Eyed Peas star on Saturday night with her cover of True Colours.
He raved: "I liked the tone of your voice, the rasp, it made me want to turn around and see who was singing it."
Explaining the choice between Will and Tom, Kate said this week: "I chose will because I absolutely love him because I have so much respect for him, I have respect for Sir Tom too but I really wanted Will and I loved that it happened."
She added: "For Danny to say I will go far makes me believe in myself, if he believes in me, than so can I.”
Speaking after her audition this weekend, the singer went on: "It's just such a massive thing, it's not just a competition on television, it’s what I want as a career.
“I’m just going to act so hard."