Having already won the Premier League and FA Cup, Pep Guardiola's side are on course to win the treble this season.
Walker missed the Champions League group stages through injury but played a key role in their knockout stage victories en route to the final.
The right-back plays a pivotal role in the City defence and will likely be a key player should he make an appearance against Internazionale.
However, Walker's fitness ahead of the European showdown is in question as Guardiola revealed why he missed training.
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Speaking on the England international, the City boss said: "He had a disturbance in his back.
"Yesterday it was not good, and today a little bit better. We don't want to take risks and we'll see what happens in the next days."
City have progressed through this season's Champions League unbeaten and conceded just five goals.
Saturday night will be their second appearance in the final after their heartbreak in 2021 when they lost to Chelsea.
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Walker started and played the full 90 minutes in the defeat, with he and his fellow City stars keen to make it second time lucky.
Victory against Inter would signal the club's most successful season in their history and see them finally claim the coveted European crown.
Guardiola has already won the Champions League twice, and will become only the third manager to lift it three times should City emerge victorious.
talkSPORT will have live coverage of the Champions League final between Man City and Inter Milan on Saturday night.