Conor McGregor has a pretty powerful supporter -- with Chuck Liddell telling TMZ Sports the Irishman is right ... his fight with Donald "Cowboy" Cerrone should be promoted as the MAIN event.
Remember, Cowboy told ESPN this week ... fight negotiations broke down because Conor refuses to be billed as a co-main event.
The issue is that neither Conor nor Cowboy currently hold a title -- so they would share the main event billing with whatever title fight would take place on the same card.