UFC 200: Anderson Silva steps in to fight Daniel Cormier
Anderson Silva will fight Daniel Cormier at UFC 200 on Saturday following the withdrawal of Jon Jones.
Silva has not fought since losing to Britain's Michael Bisping in February.
Given the late notice, the pair will meet in a three-round, non-title light-heavyweight contest.
Light-heavyweight champion Cormier, 37, was originally scheduled to take on Jones in Las Vegas, but that fight fell through when Jones failed a drugs test.
Brazilian Silva, 41, was the longest reigning champion in UFC history until he lost his middleweight title to Chris Weidman in July 2013.
Jones tested positive in an out-of-competition sample collection by the United States Anti-Doping Authority (Usada) on 16 June.
In a news conference on Thursday, he apologised to Cormier, saying: "I know this fight means a lot to him. And it means a lot to me."
Jones said he had taken the same supplements as he did before previous fights and that anything different was not performance-enhancing.
His manager, Malki Kawa, said they will not name the substance until a B sample is tested by Usada.
"Right now, I'm trying to think of everything I've taken," Jones added. "The whole thing sucks. If I do have to serve two years then I will definitely be back."
The women's bantamweight title fight between Miesha Tate and Amanda Nunes has been promoted to the main event slot at UFC 200.
The heavyweight fight between American Brock Lesnar and New Zealander Mark Hunt will now be the co-main event.