On Tuesday night, fans got a huge surprise during Taylor Swift's concert at the Staples Center in L.A. -- Justin Bieber made an appearance! "Who wants to see my friend Justin?" Taylor asked, before inviting Justin onstage with her and performing "Baby" with him.
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This isn't the first time Taylor has sang "Baby" during her Speak Now tour -- she paid tribute to her famous friend Canada and performed the song at her show in Toronto. Watch Justin's and Taylor perform "Baby" below.
"@Taylorswift13 has been there from day one. True friend. #goodtimes," Justin Tweeted afterward.
What do you think of Justin Bieber and Taylor Swift's performance? Do you think they should duet together more often?
Photos: Courtesy of Sirius XM; Dave Allocca/Startraks Photos