UFC 173

UFC 173: Barão vs. Dillashaw was a mixed martial arts event held at the MGM Grand Garden Arena in Las Vegas, Nevada on May 24, 2014.

Background
A Middleweight Championship bout between then champion Chris Weidman and number one contender Vitor Belfort was scheduled to headline this event. However, on February 27, the Nevada State Athletic Commission officially banned testosterone replacement therapy (TRT) from combat sports. Belfort, who was using such therapy, was forced to withdraw from the bout and stated, "Given the time constraints involved between now and my proposed next bout in May, I have determined not to apply for a license to fight in Nevada at this time."

The main event was quickly changed as former UFC Light Heavyweight Champion Lyoto Machida agreed to step in to face Weidman for the title. However, on March 24, the UFC announced that Weidman had suffered a knee injury and that a new headline bout would be found. The Weidman title defense against Machida was moved to UFC 175 in July.

After the announcement that Weidman/Machida bout had been moved, a Bantamweight Championship bout between Renan Barão and Raphael Assunção was targeted as the event headliner. However, Assunção opted to decline the bout as a rib injury sustained in his last bout at UFC 170 had not healed enough to resume the proper training in advance of the event. Barão instead fought T.J. Dillashaw in the main event. As a result, Dillashaw's original opponent at the event, Takeya Mizugaki, faced Francisco Rivera.

The originally scheduled co-main event was Junior dos Santos against Stipe Miocic. However, that bout was moved to The Ultimate Fighter Brazil 3 Finale. Subsequently, the bout between Dan Henderson and Daniel Cormier, briefly linked to UFC 175 was moved up to this event to bolster the card.

The coaches bout between The Ultimate Fighter: Brazil 3 participants Chael Sonnen and Wanderlei Silva was briefly linked to this event. However, the fight was moved twice – first being on May 31, 2014, at The Ultimate Fighter: Brazil 3 Finale, then it was to be contested on July 5, 2014, at UFC 175 but the fight eventually was called off for various reasons.

A lightweight bout between Yves Edwards and Piotr Hallmann was expected to take place at this event. However, the fight was moved to UFC Fight Night 42.

Kyung Ho Kang was expected to face Chris Holdsworth at the event. However, Kang pulled out of the bout and was replaced by Chico Camus.

Doo Ho Choi was expected to make his promotional debut at the event against Sam Sicilia. However, Choi was forced out of the bout with an injury, and was replaced by UFC newcomer Aaron Phillips.

Danny Mitchell was expected to face promotional newcomer Li Jingliang. However, Mitchell pulled out of the bout with an injury. Replacing Mitchell was The Ultimate Fighter: Team Carwin vs. Team Nelson cast member David Michaud.

Bonus awards
The following fighters were awarded $50,000 bonuses:
 * Fight of the Night: Renan Barão vs. T.J. Dillashaw
 * Performance of the Night: T.J. Dillashaw and Mitch Clarke

Reported payout
The following is the reported payout to the fighters as reported to the Nevada State Athletic Commission. It does not include sponsor money and also does not include the UFC's traditional "fight night" bonuses.
 * T.J. Dillashaw: $36,000 (includes $18,000 win bonus) def. Renan Barão: $74,000
 * Daniel Cormier: $170,000 (includes $85,000 win bonus) def. Dan Henderson: $100,000
 * Robbie Lawler: $200,000 (includes $100,000 win bonus) def. Jake Ellenberger: $68,000
 * Takeya Mizugaki: $58,000 (includes $29,000 win bonus) def. Francisco Rivera: $15,000
 * James Krause: $20,000 (includes $10,000 win bonus) def. Jamie Varner: $17,000
 * Michael Chiesa: $40,000 (includes $20,000 win bonus) def. Francisco Trinaldo: $12,000
 * Tony Ferguson: $40,000 (includes $20,000 win bonus) def. Katsunori Kikuno: $10,000
 * Chris Holdsworth: $30,000 (includes $15,000 win bonus) def. Chico Camus: $12,000
 * Mitch Clarke: $20,000 (includes $10,000 win bonus) def. Al Iaquinta: $14,000
 * Vinc Pichel: $16,000 (includes $8,000 win bonus) def. Anthony Njokuani: $20,000
 * Sam Sicilia: $20,000 (includes $10,000 win bonus) def. Aaron Phillips: $8,000
 * Li Jingliang: $16,000 (includes $10,000 win bonus) def. David Michaud: $8,000