On last night's WWE SmackDown FOX premiere and 20th Anniversary special, UFC heavyweight fighter Cain Velasquez made his WWE debut by having a short brawl with the new WWE Champion Brock Lesnar, who had just crushed Kofi Kingston to win the title in the main event.

The storyline is that Velasquez was brought to WWE by Rey Mysterio, following the attack on Monday's RAW that saw Lesnar destroy Rey and his son, Dominick. Velasquez previously defeated Lesnar for the UFC Heavyweight Title back in 2010, and WWE plans to build off that fight between the two big men.

After last night's show, Renee Young spoke with Velasquez who said he's in WWE for Lesnar's attack on Rey and his son.

"I'm here because Brock Lesnar knows what he did," Velasquez said. "It wasn't right, I saw it. I'm here to get some payback."

It was reported Velasquez vs. Lesnar would likely take place at WWE Crown Jewel on October 31 in Saudi Arabia, or at WrestleMania 36 on April 5, 2020 in Tampa, Florida.

Velasquez remains under contract to UFC and has recently expressed interest in fighting again. Despite those comments, it looks like Cain is done with MMA after reportedly telling UFC officials of his intention to withdraw from the US Anti-Doping Agency (USADA) testing pool, which effectively retires him from active MMA competition.