The Brazilian phenom was slated to settle his beef with the Irish upstart on July 11 in Las Vegas, but a rib injury he suffered during training ultimately led Aldo to remove himself from his main event showdown with the Dublin native.
Former two-time title challenger Chad Mendes was tapped to be the official replacement, and the Team Alpha Male staple will now face McGregor for the interim featherweight championship in the card's showcase bout.
While Mendes' stepping in to face McGregor became official on Tuesday, per UFC President Dana White's announcement on ESPN's SportsCenter, the California-based powerhouse had been on standby since news of Aldo's injury surfaced last week.
Over that stretch, confusion hung heavily over the situation, as the UFC published a report stating the featherweight champion did not have a fracture but bruised ribs and cartilage damage.
The varying accounts of the severity of Aldo's injury coupled with McGregor's continued attacks on the longstanding titleholder continued to cast doubt about the severity of the Nova Uniao representative's injury. On Wednesday afternoon, the pound-for-pound great broke his silence in an interview with Brazilian outlet Globo (h/t Damon Martin of FoxSports.com), where he also published X-rays as proof of his broken rib:
For three months, every day, I conducted three training sessions. I invested my time and money, bringing in training partners, both in the country and outside, to make the best camp of my life and be ready to defend, for the eighth time, my belt on July 11. Unfortunately, I suffered a broken rib in training, which is proven by an official report.
The decision was taken in respect of fans and the UFC, who now consider me the best fighter pound-for-weight world. I could not fight without having 100 percent of my physical condition. Many people told me to fight anyway, due to the money that I could win, but I wouldn't sell myself, no matter what it may be.
I fight for love of what I do and for my country.
With McGregor and Mendes set to square off for an interim title, the promotion put into play following Aldo's withdrawal at UFC 189 will set up a scenario where the winner of the featherweight title tilt will face Aldo once he's healed later in 2015. Junior is the only man to hold the undisputed 145-pound strap since the promotion merged with the WEC back in 2011.
Prior to competing inside the Octagon, the 28-year-old Manaus native held the WEC featherweight title and had successfully defended it on two occasions before coming over to compete under the UFC banner.
While Aldo admitted in the interview that being forced to remove himself from the fight was a great disappointment, the striking ace wasn't exactly keen on the UFC's implementation of an interim title in his absence:
The Octagon is my kingdom and there is only room for a king -- it's me. If he wants to participate, you have to be the court jester. If you beat Chad Mendes, the only thing you'll have is a toy belt to show friends, drunk in the bars of his country, because that's what an interim title is for me -- a toy. The champion is me.
Aldo is currently in the midst of one of the most impressive runs in MMA history, as his current 18-fight winning streak has kept him out of the loss column for a decade. During that time, he's risen to be recognized as the pound-for-pound best fighter in the world, and seven consecutive successful title defenses have kept him firmly positioned at the top of the featherweight ranks.
Duane Finley is a featured columnist for Bleacher Report. All quotes are obtained firsthand unless noted otherwise.