An exclusive preview clip of 'Glee's' highly anticipated Superbowl episode has finally been unveiled. 

Despite being only 21 seconds long, the preview packs a punch and manages to fit in the main story lines of the episode. We see Puck swinging his acoustic guitar at someone, Sue Sylvester getting a tattoo of her own face and the cast wearing the same bright blue wigs that Katy Perry wore in her 'California Gurlz' video. 

The clip closes with a sneak peak at the cast's 'Thriller' performance and it looks set to he a high-octane episode. Check it out here: