The Blues were keen to steal a march on their rivals by launching a late move to sign the 18-year-old last week.
A £23m offer, however, was rejected by the Belgian giants as Chelsea continue to monitor his situation.
There will likely be more interest in the teenager when the transfer window reopens in January, with as many as 20 clubs scouting him.
Nusa is a quick and skilful dribbler playing for the Norwegian U21 side but is yet to be capped at senior level.
He has made 10 appearances this season, scoring once and helping former Celtic manager Ronny Deila’s team into the Europa Conference League group stage.
Speaking to TV2, Nusa said: “I’m in a situation where I want the next step, when it happens, to be something I’ve really thought through. I want to find what is right for me. It is important to me. I think about what is best for me.
“It is a lot of money. Much money. But I try not to think about it too much. I can’t focus on it, like. I don’t think it’s good for me.”