On a breezy summer night last August, a sea of Irish flags and green apparel filled the TD Garden.

While the start of another Celtics season was still months away, a packed house of nearly 15,000 screaming fans was in attendance for the Ultimate Fighting Championships’ first event on the then newly formed Fox Sports 1 network. Despite the promotion bringing in a number of high-profile names and notable local fighters, no one drew a bigger applause from the crowd than Irish featherweight Conor McGregor.

Walking into the Octagon to a mix of Sinéad O’Connor’s “She Moved Through The Fair’’ and The Dropkick Murphy’s “I’m Shipping Up to Boston,’’ the fans erupted for the man they call “Notorious’’—even though it was just his second fight in the UFC.


Eventually going on to defeat his opponent Max Holloway via unanimous decision, the night couldn’t have been a more perfect stateside debut for the Dublin native.

“It was a beautiful thing,’’ McGregor recently told Boston.com in a phone interview. “There were shamrocks everywhere. Every corner there was an Irish bar.’’

“Boston is a phenomenal city, I look forward to going back one day—hopefully soon.’’

Set to face Dustin Poirier in the co-main event slot on Saturday’s UFC 178 pay-per-view card, it’s clear that McGregor’s star power has only grown since his successful trip to the Hub last year.

This weekend’s bout is by far his biggest test to date, but when he looks back on his career, it likely won’t mean as much to McGregor as his headlining battle in Dublin against Diego Brandao this past July.

Coming up victorious against the Brazilian in front of his hometown fans in the Emerald Isle will be an experience the Irish fighter will remember forever.

“Yeah, you know, Dublin was something special. It was one of those rare occasions where you didn’t have to be in the arena and you could still feel the energy that was in that building, the atmosphere that was there,’’ McGregor said. “We are the fighting Irish. We love to fight, you know. It was no surprise to me, but it was something I will take with me for the rest of my life. I will look back on that with great pride.’’

New England Patriots owner, Robert Kraft (right) congratulated Irish fighter Conor McGregor after his victory at the TD Garden on Aug. 17, 2013. With just three fights in the UFC under his belt, the man they call “Notorious’’ is already poised for super stardom. —Colm O'Molloy/The Boston Globe


Another reason why Saturday’s fight with Poirier may not feel like such a big deal to McGregor is because he thinks he’s already competiting at a level above the rest of the UFC’s featherweight division.

Call him cocky or confident, it doesn’t matter to “Notorious,’’ who sees a win at UFC 178 as not just a possibility, but an inevitability.

“I am No. 1, I am the king and the rest are contenders that don’t even come close,’’ McGregor said. “Saturday night we will prove that. Sept. 27, we’ll learn the difference between a king and a contender.’’

If all goes according to plan, McGregor hopes he’ll be next in line for a featherweight title shot. The Irish fighter believes that he’ll take on either champ Jose Aldo or current No. 1 contender Chad Mendes, who’ll square off in a championship match-up at UFC 179 later this year.

Regardless of who he faces next, McGregor is focused on the task at hand, and that’s putting away Poirier.

Even though he’ll be thousands of miles away from his friends and family, when the cage doors close on Saturday night, “Notorious’’ knows he’ll have a whole nation cheering him on.

“I am always honoring the Irish fighting heritage when I step inside the Octagon,’’ McGregor said. “We are the fighting Irish, we are a nation. We came through battles our whole life. This is what we do best—we fight.’’