Cotto (38-4, 31 KOs) officially finished the 33-year-old Rodríguez (28-7-3, 16 KOs) at 18 seconds into the decisive frame.
A four-time world titlist in three weight divisions, Cotto is now training with Freddie Roach and the duo focused on throwing more left hooks to the body against Rodríguez.
Accordingly, the Puerto Rican icon landed 29 of his 55 blows to Rodriguez’s torso.
"All of the work that we put in over the last month really showed tonight," said Cotto, 32, who fought valiantly in losses to legends Floyd Mayweather and Manny Pacquiao. "I'm very happy to have Freddie in my corner. We were able to get back to basics.”
Roach agreed with Cotto’s assessment and mentioned the possibility of a rematch versus Floyd Mayweather.
"Miguel told me that if he were in the shape that he's in right now he would have won that fight," said Roach, 53, who has been voted Trainer of the Year on four occasions by the BWAA. "So I'm sure he would definitely welcome a rematch."
Despite bloodying the reigning pound-for-pound king, Cotto was unanimously outscored by Mayweather (45-0, 26 KOs) in May 2012.
Nevertheless, Cotto looked reenergized in “The City Beautiful” and far more formidable than the version that fell to “Pretty Boy.”
Rather than fighting a human chandelier like Amir Khan, Mayweather should consider giving Cotto another opportunity this May.
“If he were in the shape that he's in right now,” Miguel Cotto would be Floyd Mayweather’s toughest challenge yet.