Brock Lesnar lost his last MMA fight against Cain Velasquez. But instead of getting back into the MMA cage, he might be headed back to the WWE.

In a strange two-minute video clip Ariel Helwani shot for (we have it inside), WWE wrestler Mark Calloway (aka "the Undertaker") had a brief stare down with Lesnar as the former champ walked by.

Calloway even said the words "You wanna do it?" to Lesnar, who instead kept walking.

This might not be the best business decision for Lesnar.

And here's why.

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