The hosts snatched an 88th minute winner thanks to Serbian Milos Dimitrijevic’s later strike as the Chinese Super League heavyweights were brought crashing down to earth.
Guangzhou’s side reportedly earns more than five times the entire Sydney squad does, and they have spent lavishly since winning last year’s tournament.
But they were undone in Australia, Robert Stambolziev giving Sydney the lead on 18 minutes before an Aaron Calver own goal seven minutes later levelled things up.
The score remained level until Dimitrijevic snatched all three points for his team.
Elsewhere in the day’s early fixtures, Gamba Osaka were held 1-1 at home by Melbourne Victory and Pohang Steelers beat Urawa Red Diamonds 1-0.
