The upcoming trailer features Rachel, played by Lea Michele, singing "No One Is Alone" from Sondheim's musical Into the Woods.
The episode will also feature Rachel and Blaine, played by Darren Criss, joining forces on the Sondheim tune "Broadway Baby," from the musical Follies, according to TVLine.com.
"It's an anthemic Broadway song, we love Stephen Sondheim and we're Broadway theatre geeks that love singing this kind of music," Criss said in the interview.
"I sang this song when I was like eight years old. It was nice!" Michele added.
The Fox hit musical series heads to New York for the second half of the year, following Michele's character as she prepares to star in a Broadway revival of Funny Girl. "Glee" is produced by Ryan Murphy Television in association with 20th Century Fox Television. Murphy, Brad Falchuk, Ian Brennan and Dante Di Loreto serve as executive producers.
Visit Fox.com/Glee.
Watch the trailer below.
