The Spanish striker picked up his fifth booking of the season against Crystal Palace and is therefore suspended for the showdown with Bournemouth.
“It’s a big blow because he’s a top striker,” Courtois said.
“He scored his 13th goal of the season and he’s in top form.
“He’s been one booking away for many games now, so if he’d had a bit more luck he would have stayed like that until the New Year, when it’s gone, but hopefully Michy, or whoever the manager plays there, will do well.
“For the manager, it’s not easy to choose players.
“With Cesc, Michy, Pedro, Ivanovic and Zouma we had a good bench and to be champions you need not only 11 players, but 18 or 22, the whole squad.
“We have a good team and we try to prove that every week.”