The manager told the Liverpool Echo: "We'll have to assess him on Monday and Tuesday to see how fit he is because there is a big question mark over Rom being fully fit for the weekend.
"We've got a great relationship with the Belgian federation and it's been great to be able to work together. Obviously Rom has been struggling with that toe and he's done magnificently to be on the pitch and helping us on matchday. But this week it's been important for us to give him a specific treatment to work on that [toe] and make sure that his recovery time has been exactly what he's needed.
"It's important that we've got good relationships with the federations and, in this case, with Belgium, we've worked hand-in-hand. We hope that Rom can benefit from that."
Lukaku became the club's record signing when he joined on a permanent deal from Chelsea earlier this year, costing the Toffees £28m.