Lesnar will put the title on the line against Reigns on August 19 at the Barclays Center in Brooklyn, New York following months of animosity between the two RAW superstars.
The Big Dog has been questioning the Universal Champion’s work ethic and passion for the business due to his limited part-time schedule and rare appearances.
Reigns also thinks The Beast is more interested in UFC following his intense confrontation with Daniel Cormier at UFC 226.
The three-time world champion launched another scathing promo on Lesnar’s advocate Paul Heyman and warned him that he will leave his client a broken man next month at WWE’s biggest Pay-Per-View event of the summer.
The ex-WWE Champion said: “I have absolutely zero respect for that fool.
“The guy never shows up, he never has time to actually come to work but oddly he has plenty of time to show up to the UFC.
“He has plenty of time to walk up in that Octagon, get in Daniel Cormier’s face and run his mouth.
“If Brock Lesnar shows up to SummerSlam I’m gonna send him back to UFC, but he’s not going back as The Beast. He’s going back as Roman Reigns’ b*tch.”
Lesnar’s last WWE match took place at the Greatest Royal Rumble three months ago in Saudi Arabia where he beat Reigns in a controversial Steel Cage Match.
The former Shield star speared the champion through the cage but wasn’t awarded the belt even though his feet touched the floor first.
The Conqueror is linked with a big UFC title match against Cormier at some point next year.
Lesnar confronted the UFC Heavyweight Champion and UFC Light Heavyweight Champion at the T-Mobile Arena.
The ex-UFC Heavyweight Champion walked into the Octagon after DC called him out following his historic first-round knockout victory over Stipe Miocic, which made him the second fighter in UFC history to hold two titles simultaneously.
Moments after coming face-to-face the five-time world champion nearly sparked a brawl by pushing the new two-division champion before delivering a profanity-laden tirade.