Belal Muhammad's first defense of his UFC welterweight world title will have to wait ... as the champ has been forced out of his main event fight at UFC 310 after suffering a nasty bone infection.
The 36-year-old revealed the news Tuesday morning ... showing off the ailment before going under the knife, and we're not doctors, but it's safe to say a human toe probably shouldn't be that swollen!
"Caught a bone infection in my foot .