Conor McGregor will challenge for Jose Aldo’s UFC featherweight title later this year if he defeats Dennis Siver on Sunday at UFC Fight Night 59. That much, at least, is a certainty.

What’s far less certain, though, is where exactly the featherweight championship showdown will take place.

Three locations have been in the discussion: Ireland, Brazil and Las Vegas.

For some time McGregor’s native Ireland appeared to be the leading candidate, but various sources have told MMAjunkie that Las Vegas is now the target destination. Even UFC President Dana White recently suggested (via a Twitter Q&A) Sin City could host the fight. That said, McGregor must win his fight before such plans are set.

Croke Park in the Irish capital of Dublin was the rumored destination if the event took place in McGregor’s neck of the woods. The stadium can hold roughly 90,000 fans, which would obliterate the current UFC attendance record of 55,724 set with UFC 129 in Toronto.

While it’s always nice to break records, UFC Chairman and CEO Lorenzo Fertitta said it’s about more than that. For him, a sellout in Ireland is a given; it’s the logistical challenges involved that force reservations.

“There’s no question he could fill a stadium; the question is what makes the most sense for the business,” Fertitta told MMAjunkie. “That’s obviously a pay-per-view fight. It needs to be in the right time zone. We would need to get variances from the city. It’s just too soon to talk about that because the event would be taking place so late in the evening.

“We’ve got to weigh all these different factors between Brazil, Ireland, Las Vegas. It’s all kind of up in the air. But could we fill it? There’s no question.”

Each country has its own individual issues. Ireland’s venue may hold the most viewers, but Brazil’s weather is far more reliable for an outdoor show. Brazil’s time zone is more suitable for stateside broadcasting purposes, but Ireland is a more convenient travel destination for European fans, who are likely to show up en masse.

Hosting the 145-pound title fight in the UFC’s home base of Las Vegas would likely be the best remedy for all parties involved. UFC officials know how to put on a mega-event in their home city, which would greatly minimize the chance of unforeseen hiccups.

The UFC rarely has a potential fight that could be hosted in various countries and still achieve massive success. That’s a sign to White, who’s never one to pass on an opportunity to make bold predictions. He believes Aldo vs. McGregor wouldn’t just be the most meaningful matchup in featherweight history, but it would jump to the top of the list as the UFC’s most important bout of 2015.

“Aldo and Conor, I think that would be the biggest fight of the year,” White said. “I think it will beat every other fight his year, and (Jon) Jones vs. (Daniel) Cormier was this year. I think this would be the biggest fight this year.”

With a nearly four-year title reign, Aldo is established as one of the sport’s top pound-for-pound talents. He’s won 18 consecutive fights and hasn’t suffered a defeat since November 2005. “Scarface” has been flawless during his UFC tenure and has defended his belt seven times.

McGregor ‘s resume doesn’t stack up, but it’s impressive nonetheless. “The Notorious” is a former two-division Cage Warriors champion who is in the midst of an 11-fight winning streak. The 26-year-old has earned all but one of his UFC victories by first-round stoppage and has earned three fight-night bonuses for his efforts.

If McGregor (16-2 MMA, 4-0 UFC) gets past Siver (22-9 MMA, 11-6 UFC) in Sunday’s FOX Sports 1-televised headliner at Boston’s TD Garden, he would have the second longest winning streak in the division and solidify his shot at Aldo (25-1 MMA, 7-0 UFC).

Two passionate fan bases back each fighter, and whether it takes place on Aldo’s turf, McGregor’s turf or in neutral territory, White has hefty expectations.

“Part of making a big fight is a lot of people giving a sh-t,” White said. “When you have that much buzz and that much rumble, and you’ve got the most marketable fighter of all time, who’s backing up what he says versus a guy that hasn’t lost a fight in nine years, and coming off the fight he just had in Brazil – which, I was honored to sit in that seat I was in and watch what went down in Brazil that night – and now these two would be facing off? I think that would be the biggest fight of the year.”

For more on UFC Fight Night 59, check out the UFC Rumors section of the site.