For the second time in seven months, a defending UFC champion has pulled out of a title fight against Conor McGregor.

UFC lightweight titleholder Rafael dos Anjos (25-7) has withdrawn from a scheduled defense against McGregor in the main event of UFC 196 on March 5 with a broken foot.

UFC lightweight Nate Diaz has agreed to step up on short notice to face McGregor in Las Vegas, according to Dana White.

"We called Jose Aldo; Jose Aldo turned the fight down," White said on SportsCenter on Tuesday night. "We called Frankie Edgar; Frankie Edgar turned the fight down. Those are two guys everybody was talking about.

"A lot of guys wanted this fight but we ended up with Nate Diaz. We felt this was the fight to make and the fight the fans wanted to see."

Rafael Dos Anjos has a foot injury and will not be able to fight Conor McGregor at UFC 196. Joe Camporeale/USA TODAY Sports

Diaz (18-10) isn't a title contender, but the entertaining brawler from Stockton, California, is one of the UFC's most popular fighters in his weight class.

Diaz tweeted a response to the McGregor camp's previously expressed interest in facing him earlier Tuesday:

He's going to have to get on his knees and beg... — Nathan Diaz (@NateDiaz209) February 23, 2016

Dos Anjos' manager, Ali Abdelaziz, said the broken foot is expected to take six to eight weeks to heal.

The situation is reminiscent of July 2015, when then-featherweight champion Jose Aldo withdrew from a defense against McGregor on less than two weeks' notice with a rib injury. McGregor eventually fought Aldo at UFC 194 on Dec. 12, defeating the longtime champ via knockout in 13 seconds.

UFC 196 will take place at MGM Grand Garden Arena. A female bantamweight title fight between Holly Holm and Miesha Tate is slotted as the co-main event.