He was originally penciled in asthe headliner in a champion vs. champion fight with Rafael dos Anjos .
The 155 - pound king pulled out of the fight due to an injury and Diaz stepped in as a last - minute replacement at welterweight .
He was originally penciled in asthe headliner in a champion vs. champion fight with Rafael dos Anjos , but the 155 - pound king pulled out of the fight due to an injury and Diaz stepped in as a last - minute replacement at welterweight .