Callejon was on the mark in victory over Champions League opponents Feyenoord.
The win was achieved without Arek Milik after he suffered a serious knee injury last week.
“If the Coach asks me to be a centre-forward, I'll do it. If he asks me to be a full-back, I'll do it," Callejon told Mediaset Premium.
“After Milik's injury, we all have to band together and help out the team. I'd have to get some advice from Mertens on how to play as a centre-forward."