Well Belgiums not by concern to be honest. Lukaku's form on the other hand is and it's pretty poor this year.
He'll be fine. He was shite towards the end of the season a long with everyone else. He didn't have a great Euros but he's only played one 90 minute game for us since his injury so he'll be a bit rusty. Once he scores one he'll be up and running again.
He's 23 and done it for years already, a dip is to be expected from time to time but there's nothing to worry about there.