Coutinho and Mane scored 13 league goals each last season and played key roles in achieving a top-four finish.
"Liverpool are blessed with some absolutely unbelievable players," Fowler said.
"If you look at the likes of Coutinho and Mane, both stood out last year.
"Mane was probably the standout player and equally as important as Coutinho. Coutinho has had a wonderful two or three years where he's been exceptional.
"He scores goals and he is the pinnacle of everything that is good with Liverpool, he's exciting to watch. We like to think that we want the team to stay exciting and he's massively important and we need him to be on top of his game as he has been."