For further reference, below is a comparison between the Koine and Katharevousa versions of the Lord's Prayer (Κυριακή προσευχή). It appears that there is significant similarity between the two versions.
Koine Greek
Πάτερ ἡμῶν ὁ ἐν τοῖς οὐρανοῖς,ἁγιασθήτω τὸ ὄνομά σου·ἐλθέτω ἡ βασιλεία...