The installment, titled "On My Way," features rival show choirs New Directions and Warblers battling at the regionals competition. Among the Warblers' numbers are a cover of the Wanted's "Glad You Came" while New Directions take on Kelly Clarkson's Billboard Hot 100 No. 1 single "Stronger (What Doesn't Kill You)."
Gustin, who plays the villain-you-love-to-hate Sebastian on "Glee," filmed a wide-ranging, lengthy video interview with Billboard on Feb. 14, where he answered more than 40 questions submitted by fans via Twitter. Watch the interview in three installments below.
The 22-year old performer discussed the secrets of "Glee's" slushies, his thoughts on Sebastian's backstory, the possibility of kissing co-star Darren Criss and his love of Instagram. He also addressed rumors of being cast as Finnick Odair in the second "Hunger Games" film (he hasn't) and how he has "such a crush" on one particular movie actress.
Gustin also said that his character's relationship with Blaine Anderson (played by Darren Criss) is a "little bit more up in the air" in the regionals episode, as compared to where they left off in the Michael Jackson-themed show. "[Sebastian] cares for Blaine, somewhere in there, for sure. It's definitely a real thing to him. But he has his priorities out of line."
While Gustin couldn't hint at what's in store for his character on "Glee," he did caution that he doesn't "know how much longer Sebastian will be around." (Cue fan panic in five, four, three...)
After the Feb. 21 installment of "Glee," the show will take a break and return with new episodes beginning on April 10. The return will feature guest star Matt Bomer (USA Network's "White Collar") as Blaine's older brother, Cooper.