Everton manager David Moyes fears it will be impossible to fill the void left by Marouane Fellaini's absence while the midfielder is banned.
The Belgium international misses Saturday's Premier League trip to West Ham as he starts a three-match suspension.
Fellaini received the ban after television footage showed him headbutting Stoke captain Ryan Shawcross during last Saturday's 1-1 draw at the Britannia Stadium.
The 25-year-old will also miss forthcoming home games against Wigan, on Boxing Day, and Chelsea, on December 30, but will be available to return for the trip to Newcastle on January 2.
And Moyes has hinted that he may have to change his team's style of play while Fellaini is out, because he does not have any other player quite like him.
The Everton manager said: "I don't know if anybody can fill the void of Marouane. I think he's an individual player.
"I may have to alter the way we play a little bit without him, so we'll look at it and see if we can find the right solution.
"I don't think you work on something like that, but now that we know we've not got him, we've been on it. But I don't think you work without someone beforehand; there's no need and there's not the time to.
"When these things happen, you have to deal with it and find solutions and, I've got to say, it's not an easy one to find."