Conor McGregor will attempt to make UFC history on November 12 when he takes on lightweight champion Eddie Alvarez at UFC 205 at Madison Square Garden.
UFC returns to New York for the first time since a 1997 ban on professional mixed martial arts was lifted earlier this year, as reigning featherweight champion McGregor attempts to become the first fighter to hold two belts simultaneously.
UFC president Dana White had previously stated McGregor would have to defend or vacate his 145lbs title before taking another fight above the weight class, but confirmed on Monday night that the Irishman will retain that belt through UFC 205.
"This is the fight the fans wanted, and I'm excited that our very first event at Madison Square Garden will be headlined by Eddie Alvarez defending the lightweight title against Conor McGregor," White told ESPN. "This card has three world title fights and is the best card in UFC history."
UFC 205 will also feature welterweight champion Tyron Woodley (16-3) defending his title against Stephen Thompson (13-1) and Joanna Jedrzejczyk (12-0) defending her strawweight title against Polish compatriot Karolina Kowalkiewicz (10-0).
McGregor (20-3) will attempt to join BJ Penn and Randy Couture as the only fighters in UFC history to win titles in multiple weight classes, though neither held titles simultaneously.
The 28-year-old was scheduled to attempt the feat at UFC 196 in March but then-champion Rafael dos Anjos withdrew with an injury and McGregor lost to late-notice replacement Nate Diaz, a defeat he avenged at UFC 202 in August.
Alvarez (28-4) won the title in a first-round knockout over Dos Anjos in July. The 32-year-old has held a 155lbs title in Bellator MMA and is 3-1 in the UFC with wins over Gilbert Melendez and Anthony Pettis coming after a loss to Donald Cerrone in his debut.
One man who is not happy with the announcement of McGregor's fight against Alvarez is undefeated number one lightweight contender Khabib Nurmagomedov (23-0).
The Russian was issued with a bout agreement by the UFC to fight Alvarez at UFC 205 and subsequently UFC 206 in Toronto in December but the champion held out for what will be a far more lucrative bout with the sport's biggest pay-per-view star McGregor.
Nurmagomedov took to Twitter on Monday to voice his frustration: "I have two bout agreements that (so-called) champ refuses to sign. I got used the whole time to make Conor and Eddie get on their knees and beg."
Interim featherweight champion Jose Aldo (26-2) is also unlikely to be pleased at being forced to extend his wait with for a rematch with McGregor. The Irishman knocked out the long-time 145lbs champion in just 13 seconds in their fight in December of last year and the Brazilian has been vocal in his desire to exact revenge.
Both Alvarez and McGregor are due to attend a press conference at Madison Square Garden on Tuesday, which is scheduled to begin at 11pm GMT.