Paul Rudd and Jimmy Fallon have a lip sync battle on "The Tonight Show."

Jimmy Fallon has learned a valuable lesson in Week Two of his "Tonight Show" run: Never ever challenge Paul Rudd to a lip sync contest unless you're prepared to go all out.

On Tuesday night's show, Rudd and Fallon had "Tonight's" first such contest. The rules were simple: two songs were selected. Neither competitor knew what the other picked. And the winner was the person who lip synced the best.

As a guest on the show, Rudd had the honor of going first, and his selection was Tina Turner's "You Better Be Good to Me." Rudd gave an impressive showing, but Fallon would not be outdone.

PHOTOS: Jimmy Fallon's 'Tonight Show' debut

The "Tonight" host countered with Foreigner's "Jukebox Hero." Fun, energetic, a typically Fallon-esque performance.

But not even Fallon could top Rudd's final song, a blistering lip syncing of Queen's "Don't Stop Me Now."

How awesome is it? So awesome that Fallon didn't even bother to do his second song.

"I concede!" he yelled. "The winner right there!"

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