Never mind Captain America vs. Iron Man, Marvel's real "Civil War" is happening Thursday night on Spike in the "Lip Sync Battle" between Clark Gregg (Phil Coulson of "Marvel's Agents of S.H.I.E.L.D.") and Hayley Atwell (Peggy Carter of "Marvel's Agent Carter").

The Dubsmash rivals will perform two songs each, per usual, and Spike has already shared some teases -- one of Gregg taking on Britney Spears's "Toxic" (KEEP THE COSTUME) and another of Atwell rocking The Offspring's "Pretty Fly (for a White Guy)":

Gregg's teaser clip already has more than 1.8 million views, so you know fans are excited (or traumatized) to see more.

Based on the teaser photo below, we know Atwell's second performance is going to be particularly bold, but there are no sneak peeks for that one yet.

"Lip Sync Battle" airs Thursday, April 21 at 10 p.m. on Spike. Who are you rooting for in this Marvel(ous) showdown? Next week's battle is Joel McHale vs. Jim Rash, but do you think they will they ever get Chris Evans to take on Robert Downey Jr.?

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