UFC President Dana White announced that Aldo (25-1 MMA, 7-0 UFC) would be pulling out of the fight against McGregor (17-2 MMA, 5-0 UFC) on Wednesday morning (AEST).
Aldo, the UFC featherwight champion was due to face Ireland’s Conor McGregor in Las Vegas on July 12 (AEST).
“Aldo’s rib is too painful and he will not be fighting,” said White.
White confirmed that an interim featherweight bout will go ahead, with American Chad Mendes filling Aldo’s place for the title against McGregor.
“Chad Mendes will fight Conor McGregor for the interim belt… I don’t feel great about it," said White.
“We’ve spent a lot of money promoting this fight and a lot of people were excited - it’s definitely disappointing."
Aldo suffered the injury while training in Brazil last week, with the seven-time defending champion waiting until the last minute to pull out of the bout.
The build-up to the Aldo-McGregor fight has been enormous, with the UFC playing on the hatred these two stars share for one another.
It is a shocking blow for the UFC, with fans looking forward to the bout for months.
The build-up to the bout has been fiery to say the least, with rumours of failed drug-tests on the part of Aldo doing the rounds in some MMA circles.
To fuel this fire, Aldo accused McGregor of taking performance enhancing drugs, before one of the Brazilian's drug tests was botched, when an official taking a unrine sample on behalf of the Nevada State Athletic Commission did not have a valid work visa in the United States.
Subsequently, Aldo's sample was thrown out, and a new test had to take place a number of days later.
BREAKING: Jose Aldo pulls out of UFC 189. Conor McGregor will now fight Chad Mendes for interim title. pic.twitter.com/5LVM3AGZLV
— SportsCenter (@SportsCenter) July 1, 2015
"If a man is scared for his life, we cannot force him to step inside & face me." - Conor McGregor on Jose Aldo http://t.co/NOVzVulXVH
— SportsCenter (@SportsCenter) July 1, 2015
Dana on @SportsCenter @josealdojunior 's rib is too painful and will not be fighting at #UFC189. @ChadMendes will be in for the interim belt
— UFC (@ufc) July 1, 2015
To add to the drama, there have been conflicting reports as to how serious the injury to Aldo’s rib area actually is.
Word from the Aldo camp has confirmed that a physician had diagnosed the 28-year-old Brazilian with a fractured rib, while the official UFC statement relayed that Aldo had only suffered bone bruising and minor cartilage damage.
McGregor was not as forgiving in his assessment of the Aldo injury when asked whether he thought it was a legitimate excuse to remove himself from the fight.
“Doctors have cleared him to fight,” said McGregor.
“It’s a bruise, but he still pulled out - rightfully so, the belt should be taken from him and we will contest for the interim belt, or in my opinion, the real belt.”
The drama does present an opportunity for Mendes (17-2 MMA, 8-2 UFC) to step into the ring to contest the title.
“Of course I think about fighting Conor all the time,” said Mendes.
“Conor is a guy… (who) brought a lot of attention to the sport and to the division.
“This is a guy who has worked his way to the top, and I knew eventually I was going to fight him.”
