The 22-year-old has never before been given the task of stopping Messi, who marked his return from a groin injury by scoring in Barca's 4-0 rout over Deportivo La Coruna on Saturday.
Despite the huge ask of trying to keep the five-time Ballon d'Or winner quiet, Stones is calm heading into the clash.
In an interview with Sport360, the centre-back said: "It will be great to come face to face with them. It doesn't scare me, no. I think you have to play against the best to see how you can deal with it and it always brings the best out in you as well. I see it as an exciting challenge and one I'm looking forward to - if I'm picked to play of course.
"For me, Messi's the best player in the world, easily. He's one of a kind. I think we, as footballers, appreciate it even more when you come up against him and see what he can really do."
City boss Pep Guardiola is expected to receive a warm welcome from the opposing fans as he guided the Spanish club to 14 trophies during his four-year spell as manager.