Robert Whittaker is warning Alex Pereira not to fight fellow UFC champion Dricus Du Plessis at middleweight.

Light heavyweight champ Pereira (11-2 MMA, 8-1 UFC) expressed interest in dropping back down to 185 pounds to challenge middleweight champ Du Plessis (22-2 MMA, 8-0 UFC), who’s fresh off a fourth-round submission of Israel Adesanya at UFC 305. The last time Pereira competed at middleweight, he was knocked out by Adesanya at UFC 287. He has since dominated the light heavyweight division, but Whittaker thinks draining himself back down to 185 pounds would be detrimental to him.

“Honestly I don’t think that’s a good fight for him,” Whittaker told Submission Radio. “Yeah, I don’t think that’s a good fight for him. But also like, when you move up to light heavyweight, moving back down is tricky.

“And it’s not like you move up for one fight. He stayed up there. He’s been fighting up there for a while now. So, it would take a lot out of him to get down, and Dricus is so strong there.”

Whittaker also thinks Pereira wouldn’t be able to handle Du Plessis’ power at middleweight.

“Well, Alex gets hit, OK, and Dricus likes getting hit,” Whittaker said. “So it’s hard to see someone with the amount of power to stop Dricus from walking forward into you, and Dricus hits hard. You saw that in the fight against Adesanya. Adesanya has got like a really good chin, and Dricus was still hurting him enough to make him uncomfortable.”

Pereira (11-2 MMA, 8-1 UFC) will look to notch his third light heavyweight title defense when he takes on Khalil Rountree (13-5 MMA, 9-5 UFC) in the UFC 307 main event Oct. 5 in Salt Lake City.