The promotion announced the fight at midnight Monday.
Masvidal passed his coronavirus test, and both he and Usman will be leaving Las Vegas for Abu Dhabi later Monday, sources said. Usman will be on a charter flight, and Masvidal will fly on a private jet, according to sources.
After arriving in Las Vegas on Sunday, both fighters had to take a coronavirus test and then quarantine while awaiting the results. Had they not passed the tests, the fight would not have been able to go on.
The UFC worked to salvage Usman's presence on the card after Gilbert Burns was forced to withdraw Friday night.
For the past two months, the UFC and Masvidal were far apart on contract talks to make this fight happen. In the end, the UFC decided to walk away from negotiations about a month ago and gave the title fight to Burns, who recently beat former champion Tyron Woodley.
Afterward, Masvidal posted a series of tweets criticizing the UFC for its business practices and questioning whether the relationship would be severed for some time. But once Burns was forced off the card late Friday, momentum started to build for the original plan, which is a grudge match months in the making. Usman and Masvidal have been embroiled in a heated feud that saw the duo get into a shouting match at Super Bowl media row earlier this year in Miami.
On Saturday afternoon, Usman tweeted, "Might be time for the pig to squeal." Masvidal's co-manager posted a series of Instagram stories showing Masvidal on the phone, with the caption "negotiating."
Of course, during the coronavirus pandemic, it isn't as simple as just agreeing to a fight. Masvidal took and passed a coronavirus antibody test Saturday afternoon. That test shows whether an individual has been exposed to the coronavirus but doesn't indicate whether the person currently has the virus. The fighters still have to pass more coronavirus tests before fight night, as will all the fighters competing this month in Abu Dhabi.
Masvidal is considered one of the most popular fighters in the sport, with many believing that he was the 2019 fighter of the year after he picked up impressive wins over Darren Till, Ben Askren and Nate Diaz. In addition to the welterweight title fight, the card features Alexander Volkanovski vs. Max Holloway 2 for the featherweight title and Petr Yan vs. Jose Aldo for the bantamweight title.