It's not even close ... if Conor McGregor fights Floyd Mayweather, Muhammad Ali would've rooted for the IRISHMAN ... so says the champ's ex-wife.
"Ali don't like anybody dull, he likes everybody EXCITING," Khalilah Ali told TMZ Sports ... "He’d be a Conor McGregor [fan]. Conor McGregor's the guy."
Khalilah was married to Muhammad from '67 to '76 and has 4 children with the boxing legend.
Of course, Muhammad saw Mayweather fight ... but famously rooted for Pacquiao when they squared off in 2015.