Tonight's WWE SmackDown FOX premiere and 20th Anniversary main event saw Brock Lesnar defeat Kofi Kingston to become the new WWE Champion.

The match lasted just seconds. Kofi charged as the bell rang but Lesnar caught him in mid-move and dropped him with the F5 to get the pin for the win.

This is Lesnar's fifth reign with the WWE Title. Kofi had been champion since defeating Daniel Bryan back at WrestleMania 35 on April 7.

The bigger news coming out of the match was the WWE debut of UFC heavyweight Cain Velasquez. After Lesnar and Paul Heyman stood tall with the WWE Title, Rey Mysterio's music hit and he eventually came out with Velasquez. Lesnar and Heyman looked on from the ring, shocked. Cain entered the ring and ducked a shot from Lesnar, then tackled him. Cain pounded on Lesnar on the mat as Lesnar resisted and tried to retreat. He finally escaped the ring and stared Cain down from the ramp. Lesnar teased going back in but finally walked back to the stage as fans booed him. SmackDown went off the air with Cain standing tall in the ring with Mysterio while Lesnar and Heyman watched from the stage.

We noted before that WWE booked last Monday's RAW segment with Lesnar destroying Mysterio and his son as potential build for a Cain vs. Brock feud, if they could get Cain to sign. It's possible that WWE already had Cain signed when they did the RAW angle. Stay tuned as we should have more details behind the signing and this week's TV angles soon. It's interesting to note that Cain was wearing a brace on his knee when he came out on tonight's SmackDown. It was recently reported that Cain would likely need to undergo knee surgery before making any commitment to a pro wrestling promotion.

The 37 year old Velasquez previously defeated Lesnar for the UFC Heavyweight Title at UFC 21 back in 2010. That was acknowledged on SmackDown by Corey Graves. Cain made his pro wrestling debut back in August, and has worked two matches for AAA. He recently had talks with WWE, AEW, NJPW and AAA, before apparently inking a deal with WWE. Cain has reportedly enjoyed working a high-flying lucha style in Mexico, but it was noted that WWE wasn't interested in using him that way as they wanted to use him as a real fighter-type who could legitimately rival Lesnar. Regarding Cain's MMA future, he is still signed to a UFC contract and has recently talked about wanting to fight again. Cain's UFC deal is allowing for the work with WWE, as it did with AAA.

Stay tuned for more updates on Cain's WWE status. Below are photos and videos from tonight's title change and debut at the Staples Center in Los Angeles: