It was the duet no one really saw coming at Taylor Swift 's concert last night at L.A.'s Staples Center.
Justin Bieber was the hitmaking songbird's surprise performer...
About thirty minutes before Swift hit the stage, I did spot Bieber backstage when I was part of a group that was being given a behind-the-scenes tour by—ready for this?—Swift's mom, Andrea.
Andrea and the Biebster hugged hello, but she made no mention he would join Taylor later on for a performance of "Baby." Andrea said they were good friends and he comes to her shows whenever he can.
The more than 13,500 people in the arena went nuts as soon as they heard the band playing, "Baby." "Who wants to see my friend Justin?" Swift asked the crowd.
As if she had to ask.
Swift later tweeted, "You think you've heard LOUD screaming in your life.. Then @justinbieber comes out and does a surprise song during your show. Woah. Unreal."
The "Fearless" singer not only performed all her hits and then some last night, but she also squeezed in some Jason Mraz, Gwen Stefani and the Beach Boys. She even left the stage to do a lap around the floor, hugging and shaking hands with dozens of screaming fans. You can check out some of the footage I shot on my iPhone over at my YouTube channel.