Former 'NSYNC member JC Chasez made a surprise appearance and his friend Matthew Morrison's London concert last night, joining the 'Glee' star on stage for a duet of the boyband classic, "This I Promise You."
Morrison, who toured London in support of his recently released self-titled solo effort, will open for the Backstreet Boys and New Kids On The Block tour in the U.S. in July.
Chasez also took to the stage for a solo rendition of Journey's "Don't Stop Believing."
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