Stoke City new boy Ibrahim Afellay made his first appearance for the club but was unable to help the Premier League side avoid defeat against FC Koln in the Colonia Cup.
Afellay completed his move to Stoke earlier this week and was handed a start by Mark Hughes as the Potters stepped up their preparation ahead of the new season.
But goals from Anthony Modeste and Yannick Gerhardt, either side of Peter Odemwingie's header, gave Hughes' side plenty to think about ahead of their clash against FC Porto on Sunday.
Manchester City's final pre-season preparations stalled on Saturday as they were thumped by Stuttgart at the Mercedes Benz Arena.
Filip Kostic, Daniel Didavi and a brace from Daniel Ginczek sent the hosts flying into a 4-0 lead at half time before Kelechi Iheanacho and Edin Dzeko halved the deficit late on..
The Premier League side rung the changes at the break and added extra urgency upfront via Iheanacho.
His addition helped the Citizens limit the damage as he finished following good work from Sterling with 83 minutes played.
And Edin Dzeko, who also came on as a second-half substitute, grabbed another with just minutes of the clash left thanks to good work from Sterling again, but it proved too little too late.