The 2018 premiership cup isn't the only thing on the line at Saturday's AFL grand final.

Thanks to a bet between the WA and Victorian sports ministers the dignity of the states' sporting colosseums ride on whoever wins the Eagles and Magpies Grand Final.

If the Magpies win Optus Stadium will be lit up in their colours.

On 6PR's Perth Live program on Tuesday night WA Premier Mark McGowan issued a tongue-in-cheek bet to Victorian Premier Daniel Andrews that if the Eagles win on Saturday, Perth would host the grand final in 2019.

On Wednesday afternoon Victorian Sports Minister John Eren rejected the bet on Victorian station 3AW and instead issued a more "sensible" bet.