According to a PerezHilton.com report posted today, "Glee" star and University of Michigan grad Darren Criss thrilled a sold-out crowd at New York City's Irving Plaza on Wednesday night, singing both covers and original songs. (Criss is currently taking part in a nationwide "Glee" concert tour.)

Several Warblers—on "Glee," the show choir that Criss' character, Blaine, is part of—came on stage to accompany Criss on "Teenage Dream," among other tunes; and Naya Rivera (Santana on "Glee") made a surprise appearance to sing "Valerie" with Criss during the encore.

But perhaps the biggest surprise of the show's encore was that it included two songs (like "Gotta Get Back to Hogwarts) from Criss' U-M Basement Arts project—that became a viral sensation by way of YouTube—"A Very Potter Musical." Criss starred in, and co-wrote the music for, the show, and according to a report from EntertainmentWeekly.com, "Potter" co-star Lauren Lopez joined him on stage during this portion of the concert.

Here's a clip of Criss performing "Teenage Dream" with members of the Warblers:

And here's Criss with Rivera:

Jenn McKee is the entertainment digital journalist for AnnArbor.com. Reach her at jennmckee@annarbor.com or 734-623-2546, and follow her on Twitter @jennmckee.