we will see TMZSports.com
Khamzat Chimaev has his hands full with Robert Whittaker -- the former UFC middleweight champion -- but, he doesn't believe it'll be the toughest test of his career ... 'cause that honor belongs to Kamaru Usman.
TMZ Sports talked to 30-year-old Chimaev from Abu Dhabi just a few days before his UFC 308 co-main event against Whittaker ... when we asked him if he believed Robert was the most dangerous fighter he's faced.
"I think Kamaru is a better fighter than this guy, but we will see in the cage.