Fellaini left Standard Liege to sign for the Toffees in September 2008 and has become one of their most important players.
He suffered a serious ankle injury in the Merseyside derby against Liverpool last term which kept him sidelined until August, but Fellaini has bounced back impressively in 2010/11 and Round believes the 23-year-old will only get better.
"He is really starting to establish himself now," Round told www.evertonfc.com. "He has had a couple of years to get used to the Premier League.
"We must not forget he is still a young player and is still growing and maturing as a player. His stature and performance levels are rising all the time - day by day and game by game.
"We see it in training and we see it in matches, he is such a formidable force for us and such a big presence in the midfield."
Source: PA
Source: PA