The super-fight between Conor McGregor and Floyd Mayweather Jr. has been made official.

McGregor, the first-ever simultaneous two-division UFC Champion, and multi-time world champion Mayweather have long been considered the best counterpunchers in combat sports, and they will fight to prove who is better on August 26, 2017, at MGM Grand Garden Arena in Las Vegas.

The 5-foot-8, 151-pound Mayweather has won the WBC super featherweight, lightweight, welterweight and light middleweight crowns, along with the IBF welterweight title, WBA (Super) light middleweight and (Super) welterweight titles and WBO welterweight championship.

On his way to a 49-0 record, the 40-year old Mayweather has defeated Manny Pacquiao, Canelo Alvarez, Miguel Cotto, “Sugar” Shane Mosley, Juan Manuel Marquez, Marcos Maidana (twice), Arturo Gatti, Ricky Hatton and Oscar De La Hoya, all of whom are current or former champions across several weight classes.

Last November, the 28-year old McGregor came to Madison Square Garden looking to make history and become the first simultaneous two-division champion in the history of the Ultimate Fighting Championship, and that is exactly what he did.

Courtesy of a knockout of Eddie Alvarez in the main event of UFC 205 in New York City, the 5-foot-9, 155-pound McGregor added the UFC lightweight championship to his resume, going along with the featherweight title he won in December of 2015.

While taking a right-handed punch from Alvarez, McGregor fired off a powerful left hand that landed on the side of the defending champion’s face. McGregor followed it up with a right hand to Alvarez’s jaw, a left to the ear and another right that eventually floored his opponent.

Once Alvarez was on the mat, McGregor landed two left-handed punches, and that forced referee “Big” John McCarthy to call a stop to the bout at the 1:52 mark of the second round.

McGregor landed 40 of his 93 strikes, 32 of which were significant, according to FightMetric. Conversely, Alvarez landed only 12 strikes. Also, he was unsuccessful in his three takedown attempts.

With the win over Alvarez in the UFC’s New York City debut, McGregor successfully fought in three weight classes over an 11-month period, posting a 3-1 record in four bouts at featherweight (145 pounds), welterweight (170) and lightweight (155).

Although McGregor has never boxed professionally, he is 21-3 in his professional MMA career, and has won nine of his 10 bouts in the UFC.