Khabib Nurmagomedov can't seem to catch a break.

An injured rib has forced Nurmagomedov out of his highly-anticipated Dec. 11 fight against Tony Ferguson, sources confirmed with MMAFighting.com Thursday night.

This latest injury is particularly disheartening for the undefeated Russian because two serious knee injuries have sidelined him since his win over Rafael dos Anjos in April 2014. Despite his long layoff, the 22-0 lightweight, who by all accounts tried his best to fight through the injury but could not get cleared, is still considered one of the very best 155-pound fighters in the world.

According to sources, the UFC is now targeting Edson Barboza vs. Tony Ferguson for the TUF 22 Finale in Las Vegas, which is scheduled to be headlined by Frankie Edgar vs. Chad Mendes.

Ferguson is riding a six-fight winning streak, while Barboza has won three of his last four.