Anthony Pettis became the UFC lightweight champion a little over two weeks ago at UFC 164 when he defeated Benson Henderson. Pettis has a date and an opponent for his first title defense.

Pettis will be squaring off with former Strikeforce lightweight champion Josh Thomson in the main event of UFC on Fox 9 on Saturday, December 14.

Thomson last fought in April at UFC on Fox 7 when he became the first to ever stop Nick Diaz when stopped Diaz in the second round. The Calfornia native got the shot at Pettis when T.J. Grant announced on Twitter last night that he was still experiencing the effects of a concussion he suffered in June.

Hey people. Quick update. Unfortunately I won't be fighting Pettis on dec 14. I am still not yet 100% n can't commit to fight. UFC is going

— TJ Grant (@TJ_Grant) September 17, 2013

With someone else instead. It sucks but it is the best for both myself and the UFC. Please don't worry. Ill be back and if I gotta fight

— TJ Grant (@TJ_Grant) September 17, 2013

Someone else to get back to where I wanna be then that's what I'm gonna do. I'm not bitter. Thanks

— TJ Grant (@TJ_Grant) September 17, 2013

UFC on Fox 9 will take place at the Sleep Train Arena in Sacramento, California. Here is the updated card for UFC on Fox 9.

- Anthony Pettis vs. Josh Thomson – for UFC lightweight title
- Urijah Faber vs. Michael McDonald
- Nik Lentz vs. Chad Mendes