Taylor Swift made a surprise appearance on The Tonight Show Starring Jimmy Fallon on Monday night, where she sung "New Year's Day." The pop star wasn't scheduled to perform, but decided to give a heartfelt rendition of the Reputation tune in honor of Fallon's mother.

Last night marked the return of The Tonight Show, as the host took the week off to grieve the death of his mom Gloria. He tearfully told the crowd: 

"As some of you know, my mother Gloria passed away recently and I canceled our shows last week to be with my family and make arrangements. She was the best audience. She was the one I was always trying to make laugh, and she was such a fan of the show and everything I did. When we were little, my mum would walk us to the store—me and my sister—and we would hold hands. And she would squeeze my hand three times and say, 'I love you,' and I would squeeze back, 'I love you, too.' Last week I was in the hospital, at her side. I grabbed her hand and I squeezed, 'I love you,' and I just knew we were in trouble."

What made Swift's song selection even more sentimental is that "New Year's Day" includes these lyrics: "You squeeze my hand three times in the back of the taxi / I can tell that it's gonna be a long road." Mike DiCenzo, a writer/producer on The Tonight Show, shared his thoughts on the show and performance. "That hug between Jimmy and Taylor after the song was 100% real emotion," he tweeted. "Whatever you think of Taylor, she did something beautiful for Jimmy and our show today, and we're forever grateful."

Swift is currently promoting her Reputation album, which features "Call It What You Want," "Look What You Made Me Do," "...Ready For It?" and "Gorgeous." She'll be embarking on a stadium tour beginning on May 8 at Arizona's University of Phoenix Stadium. Next up, watch watch squad member Selena Gomez talk about her friendship with "sister" Taylor Swift below: