Conor McGregor's First Event as a Headliner in USA | On This Day *, 2015, america, anniversary, boston, conor, day, dennis, event, first, headliner, Highlights, knockout, ko, main, mcgregor vs siver, McGregor:, MMA, News & Announcements, on, siver, this, tko, UFC, Ultimate Fighting Championship, usa | January 18, 2022 10:15 pm
