The Croatian is unlikely to beat Alcaraz in Madrid though stranger things have happened. His serve is a major weapon and he won an ATP 1000 last year in conditions that favoured his serve. Madrid does as well so he can certainly make it interesting. Even so, he's fully aware that Alcaraz, as the defending champion is the favourite in the match.
He'll just go out and try to enjoy it as much as possible:
Carlos is an impressive player in incredible form. He is the favourite against me, but I will go out and have fun on the court. I will enjoy the experience of facing Carlos at Manolo Santana Stadium.
It will be the first time they play each other.