Remember when Mayweather took Mosley he had just totally destroyed the most dangerous fighter in the world in Margarito, he didn't know Shane would turn up a shot fighter. just sayin!
I don't know about "the most dangerous fighter in the world" but that was one hell of a performance from Shane, that was one of the most thrilling moments of that decade.
Was Marquez still in the top 5 when Pac won the 3rd fight? If so that's one. How high was Barrera when Pac beat him the first time? EDIT : MVC already answered.