"I would've liked to make that a lot easier, but this is the real world and it's the fight game," Faber said. "People have to understand that things will happen out there and it won't always be an easy fight. [Caceres] is a guy who has a lot of range and he's creative in the scrambles, so I wanted to make it a dirty, ugly fight."
Faber also admitted he might have been injured during the bout.
"I think I may have broken my rib in the first round at some point," Faber said. "Not sure how that happened but it might've slowed me down a bit.
"I really want to stay busy and get back in there as soon as possible. I haven't really had the chance to fight on international cards and I think that could be fun. Maybe the Japan show coming up!"
Caceres (10-5) proved to be a worthy opponent, despite facing lopsided betting odds. Vegas books closed with Faber as a 10-to-1 favorite, implying he had a 90 percent chance to win.
It appeared those odds were accurate early, as Faber scored a takedown in the first 90 seconds of the bout and went to work from Caceres' closed guard. He held top position the majority of the round, but failed to land any significant damage.
Caceres responded in the middle frame, defending takedowns and landing cleaner strikes in exchanges. He bloodied Faber's nose with a right uppercut and scored a hard knee to the rib cage from the clinch. Faber answered by taking Caceres down three times, but unlike early in the fight, couldn't keep him on his back.
With the fight's outcome up in the air, Faber brought his best in the third round. He caught a leg kick attempt from Caceres and landed a series of right hands before dumping him on his back.
A nifty transition to Caceres' back set up the rear-naked finish for Faber. It marked the 18th time he's finished a fight via submission.
Faber continues to hover around UFC title contention. ESPN.com ranked him the No. 3 bantamweight in the world heading into the bout. His friend and teammate T.J. Dillashaw will look to defend the 135-pound title against Renan Barao in August.
Caceres suffers his first defeat since February 2012.
Struve, 26, was attempting to fight for the first time since he was diagnosed with a bicuspid aortic valve -- a rare heart disorder that disrupts blood flow.