The Brazilian has seven goals and three assists in 12 Premier League games this season, putting him up there with the league's best.
O'Neil thinks the 25-year-old can become a top flight great and rival the league's biggest stars, but has challenged him to stay consistent this season.
"Knowing Matheus Cunha, he wants to be talked about with the best players in the league," O'Neil said.
"His numbers are doing that for him at the moment and he needs to maintain that level, if that's the discussions and the sort of company that he wants to keep, if he wants to be spoken about with Mohamed Salah and the guys that are scoring and assisting nearly every week.
"He needs to find a way, and we need to find a way to help him maintain this level that he's at at the moment.