The Bulgarian international will start treatment for the illness in a London hospital on Monday.
But the midfielder, who has been at Villa for six years, still opted to watch Alex McLeish's side in action against the Blues.
Villa players wore 'support Stan' messages on their training kit whilst warming up for the game.
A message of support was to be relayed over the stadium public address system five minutes before kick off.
Villa fans were also planning to show their support with an ovation after 19 minutes of the game in honour of Petrov who wears the number 19 shirt.
Villa officials are planning to talk to Petrov to find out if reports in the Bulgaria media claiming he was to retire from football are accurate.
Source: PA
Source: PA