Video: Watch UFC 166 headliner Cain Velasquez TKO Brock Lesnar in 2010

Next month, UFC heavyweight champion Cain Velasquez does battle with former champ Junior dos Santos for the third time with the title on the line.

Velasquez takes on Dos Santos in the main event of UFC 166, which takes place Oct. 19 at Toyota Center in Houston with a main card on pay-per-view following FOX Sports 1 and Facebook prelims.

Velasquez won the heavyweight title at UFC 121 in October 2010 when he stopped then-champ Brock Lesnar with punches in the first round. But then, after a layoff of more than a year, Velasquez lost the title in his first defense to Dos Santos at UFC on FOX 1.

Velasquez got his revenge this past December when he dominated JDS over 25 minutes at UFC 155 to get the title back. Now, after a win over Antonio Silva and a Dos Santos knockout of Mark Hunt, the two are set to collide for a third time in the rubber match. In the video above, watch Velasquez stop Lesnar at UFC 121 to win the title.

Then catch him Oct. 19 when he defends against Dos Santos at UFC 166 on pay-per-view.

And for the latest on UFC 166, stay tuned to the UFC Rumors section of the site.