UFC on FOX 9 has a new main event, as UFC flyweight champion Demetrious Johnson will defend his belt against Joseph Benavidez.

The fight has been moved from November’s The Ultimate Fighter 18 Finale to December after an injury to UFC lightweight champion Anthony Pettis.

Pettis, who suffered a knee injury, was scheduled to meet Josh Thomson. UFC president Dana White mentioned Pettis’ injury late Saturday night, but at that time stated he would remain on tap for the card.

No word yet on when Pettis-Thomson will take place.

The news of the fight change was made on FOX Sports Live. The new main event for TUF 18 Finale will feature Nate Diaz and Gray Maynard.