Glee took the last few weeks off, and we're still recovering from the emotional Cory Monteith/Finn tribute that aired almost a month ago. But with the show returning, the FOX musical dramedy is going for a more upbeat tone this week as they pit Lady Gaga against Katy Perry.

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FOX has released all four songs featured in Thursday's episode, "A Katy or a Gaga": Katy Perry's "Wide Awake" and "Roar," and Lady Gaga's "Marry the Night" and "Applause."

"Roar" is on Katy Perry's new album Prism, which debuted at #1 on the Billboard Top 200 and sold 286,000 copies in its first week. And "Applause" is off of Gaga's upcoming album Artpop, which will be released on November 11, though it leaked online recently and is now available to stream for free on iTunes Radio.

"A Katy or a Gaga" continues Demi Lovato's guest starring role as Dani, who's a love interest for Santana. She's one of the featured singers on "Roar." Considering this performance will have characters from both McKinley and New York, and just by looking at the lavish set design that we've seen in photos, this will most likely be the song that closes out the episode.

But Lovato's not the only big name stopping by. American Idol season 8 runner-up Adam Lambert is guest starring as Starchild, who auditions for Kurt's new band. This is the only the second time an Idol alum has appeared on Glee. The first time was with season 11 runner-up Jessica Sanchez, who played the lead singer of The Hoosierdaddies.