The Blues’ Belgium international goalkeeper spent three productive seasons on loan in the Spanish capital as he waited for an opportunity to present itself at Stamford Bridge.
He is looking forward to being back in familiar surroundings on Wednesday, but believes former Real Madrid striker Morata can expect a frosty reception from the locals at Wanda Metropolitano.
Courtois told Chelsea’s official website: “He will get a different one from me. Alvaro played a lot of games against Atletico. I think he scored, I am not sure, so for him it will be a big game against his rivals.
“For me it will be more friendly but between the 90 minutes we are playing there will be rivalry for me as well because they want their team to win.
He added on in-form Morata, who took his goal tally to six in seven games with a hat-trick against Stoke on Saturday: “We know he is a top striker. We know he has this ability and we’re very happy for him that he scored his hat-trick... a striker lives on goals and he has already scored a few important ones this season.”
While Morata is very much the present and future at Chelsea, a midweek trip to Madrid will allow the Blues to be reacquainted with a prominent figure from their recent past.
Despite helping the club to two Premier League titles, Diego Costa was deemed surplus to requirements over the summer and has now seen a £57 million return to Atletico sanctioned.
He is expected to be in attendance for a heavyweight Champions League clash, with Courtois grateful that he will not be forced to face the Spain international as he waits on his transfer to be ratified.
“He is a very good friend and it will be nice to see him there,” added Courtois.
“I am happy that until the New Year we don’t have to face him and I hope we continue in the Champions League.”