Salah has had an incredible debut season for the 'Reds', scoring 32 goals in the league to win not only the PFA Player of the Year award but also the Golden Boot.
However, this isn't sufficient for Herrera who believes Hazard is far superior to the Egyptian forward.
"For me, Hazard is the best player in the league," the United midfielder said on the 'Big Interview with Graham Hunter'.
"In my opinion he’s the best player in the league, I’ve said that since my first day here."
Herrera is set to battle it out with Hazard in the FA Cup final on Saturday as both United and Chelsea look for their first piece of silverware for the season.