UFC 166: Velasquez vs. dos Santos III was a mixed martial arts event held on October 19, 2013, at the Toyota Center in Houston, Texas.

[3] The main event was a UFC Heavyweight Championship bout between the current champion Cain Velasquez and top contender Junior dos Santos.

A bout between George Roop and Francisco Rivera was scheduled for this card, but was moved to UFC Fight Night 31 and replaced by Sarah Kaufman vs. Jessica Eye.

However, Grice was forced out of the bout after sustaining serious injuries in a September 8 car accident in his home state of Oklahoma.

[6] Grice was replaced by Charles Oliveira who also lost his original opponent, Estevan Payan, due to injury.