The former lightweight world champion made it look easier than in either of their previous two encounters, winning by technical knockout at the end of the third round.
Alvarado’s corner called it off after seeing the man called Mile High brought down to earth with a knockdown in the third and an incessant barrage of blows from the opening bell.
Rios, who took Manny Pacquiao the distance just over a year ago, moves to now 33-2-1 and said he??felt like “a new man” after completely dominating an opponent who he beat in October 2012 and but lost to on points in March 2013.
A packed crowd in Broomfield, Colarado, saw both fighters go at it again, although this time Rios led the way.
A straight right landed early on and soon both fighters were in close in an opening round that not only lived up to expectations but also had an air of the Diego Corrales-Jose Luis Casillo clash of a decade ago.
The difference was this was one-sided and the moment Rios landed an uppercut that jolted Alvarado’s head back, it suddenly looked like their third meeting would not get close to going the distance.
The second round saw Alvarado’s nose and face blooded as he took three and four-punch combinations with his defence prised wide open.
Rios stepped it up even more in the third, landing the uppercut at least four times. The only time he was kept at bay was when he was caught with a low blow. Alvarado’s illegal (34-3) left was arguably the only time he landed.
Rios closed the round with the sort of all-out assault that had seen the pair land over 3,000 punches between them in 24 rounds, but this time even the fourth round was a step too far for Alvarado.