Watch: Taylor Swift perform 'New Year’s Day' live for Jimmy Fallon.

A few words (i.e. a thread) about tonight's show. It was our first show back after Jimmy's mom passed away...

— Mike DiCenzo (@mikedicenzo) November 14, 2017

First, a quick word about Taylor Swift. She was not scheduled to do our show today. But we wanted something special for this first show back, so we asked her on a complete whim, since she had been in town doing SNL. She said yes with zero hesitation.

— Mike DiCenzo (@mikedicenzo) November 14, 2017

She sang "New Year's Day." No one had heard it. Suddenly she sings the line, "Squeeze my hand 3 times in the back of the taxi." I nearly gasped. Tears. I think everyone in the audience started sobbing.

— Mike DiCenzo (@mikedicenzo) November 14, 2017

I could see Jimmy silhouetted at his desk dabbing his eyes with a tissue. We all lost it. It was a beautiful coincidence in a beautiful performance. "Hold on to your memories, they will hold on to you," Taylor sang.

— Mike DiCenzo (@mikedicenzo) November 14, 2017

That hug between Jimmy and Taylor after the song was 100% real emotion. Whatever you think of Taylor, she did something beautiful for Jimmy and our show today, and we're forever grateful.

— Mike DiCenzo (@mikedicenzo) November 14, 2017