On Fallon's first night back on The Tonight Show desk after taking time off following the passing of his beloved mum, Gloria Fallon, who better to surprise the talk show host and comedian with a beautiful musical tribute than the queen of pop, Taylor Swift?

Fallon has spoken about how close he was to his mum and how she was the person he always aimed to make laugh - so her passing is a devastating loss for him. The crew on The Tonight Show starring Jimmy Fallon knew this and according to Billboard, Mike DiCenzo, one of the show's writer/producers said, "We wanted something special for this first show back." Enter Taylor Swift.

Billboard reports DiCenzo said, "We asked her (Taylor Swift) on a complete whim, since she had been in town doing SNL." And classy girl that she is, "She said yes with zero hesitation."

During the show Fallon spoke about his mum telling a particularly poignant story of how when he was a kid she would squeeze his hand three times and say "I love you."  So when Swift performed her song New Year's Day off her new album Reputation, which has the lyrics, "You squeeze my hand three times in the back of the taxi," Fallon and everyone on set were reduced to tears.

Watch Taylor's moving performance on The Tonight Show with Jimmy Fallon

Watch Taylor Swift bring Jimmy Fallon to tears