The burly forward endured a disastrous spell at West Ham - scoring just twice during his loan spell at Upton Park - but Rush believes the Sheffield-born player can prove his worth in the Reds first-team next season.
Rush said: "He has brought back from West Ham a hunger to score goals. It has got to be good for Liverpool that he has his confidence back.
"With Mellor the club have five quality strikers. Neil has a different style of play and sometimes when you come up against difficult opposition you need that."