The Belgium international has not featured in two successive games for United, the latest being Saturday's 3-2 win over Stoke City at Old Trafford.
"I know what I'm worth, the coach too," Fellaini told BeIN Sport. "It's the coach's choice [whether or not to start me]. He's the one who makes the decisions. I don't think anything about it. It's up to me to prove that I should play. I think he'll succeed with time. He needs time."
The 25-year-old signed for the Premier League champions on deadline day in the summer from Everton for a reported £27m fee.