Aguero was the key figure as City came from behind to beat 10-man Bayern 3-2 at the Etihad Stadium on Tuesday and reignite their push for a place in the last 16 of the UEFA Champions League.
City's talisman has demonstrated fine form this season and boasts 17 goals from 18 appearances in all competitions.
Kompany told ITV: "If you want to succeed at anything, you need a special player in special form, otherwise you just don't win anything.
"He's our special player and when he's in that form he makes things achievable that otherwise wouldn't be."
City head to Roma for their final Group E game knowing a victory will be enough to guarantee qualification, providing CSKA do not triumph at pool winners Bayern.
A score draw would be enough for Manuel Pellegrini's side if CSKA are beaten in Munich.
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