There are no guarantees that Daniel Cormier's next fight will be against Brock Lesnar.

Fresh off his defeat of Stipe Miocic to claim the UFC's heavyweight title on Saturday night, Cormier called out Lesnar, and the 6-foot-3 behemoth responded by shoving the two-division champ in the middle of the Octagon. UFC president Dana White has already all but guaranteed the two will fight for the heavyweight belt, but some hurdles need to be cleared.

"He needs to be clean. I'm not going to fight him if he isn't clean. I've done that enough," Cormier said Monday on "Ariel Helwani's MMA Show."

Lesnar last fought in the UFC in July 2016. He was later hit with a year-long suspension after testing positive for a banned substance. Six months into the ban, he retired.

Cormier is leery of fighting another opponent with a black mark on their resume. His nemesis, Jon Jones, had his MMA license revoked by the California State Athletic Commission in February after he tested positive for a steroid. His July 2017 fight with Cormier at UFC 214 was rendered a no contest as a result.

"We're going to do our testing ... through USADA, which is the gold standard ... but also we want to see if there are any extra levels," Cormier said.

Lesnar has begun the process of re-entering the USADA drug-testing pool and has to serve the remaining six months on his suspension.

In the meantime, Cormier isn't opposed to defending his light heavyweight title. He's already defeated Alexander Gustafsson and Volkan Oezdemir, the two top contenders in the division.

"You know what, I'll fight Shogun," Cormier said, to Helwani's bemusement.

Shogun Rua is currently on a three-fight winning streak and will next face Anthony Smith on July 22. Cormier said if Rua wins that fight, he'd love to face the MMA legend.