Rodríguez Jr. faced the former WBA flyweight champion and one-time interim super flyweight title challenger Hernán Márquez on 20 October 2018. He won the fight by a third-round technical knockout. Rodríguez knocked Márquez with a short left cross 30 seconds into the third round, which didn't leave his opponent visibly hurt as he was able to beat the ten-count. Rodríguez floored Márquez down with another left cross in the final minute of the round, which left him unable to rise from the canvas. Referee Florentino Lopez decided to wave the fight off at the 2:10 minute mark, without administering the full ten-count.
