It was recently confirmed that the Fox show's cast members will swap roles for a special two-hour season finale.
"I really thought I had the hardest one because they were really hard to nail - they're not over the top by any means," Colfer told TV Line.
"But it was also nerve-wracking because I didn't want to disrespect anybody!" he added.
He went on to talk about what it was like to play a new character.
"It's kind of like a switch in your mind," Colfer said. "You see yourself in a different mirror, and then you go for it!"
Glee continues Tuesdays at 8/7c on Fox. UK viewers can watch it Thursdays at 9pm on Sky1.
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