Roberto Mancini's men bit the dust against little-known Saudi Arabian side Al Hilal in their pre-season opener on Friday.
Manchester City, who won the Premier League last season under Mancini, were taken unawares during their 1-0 defeat.
Mancini, who has recently been given a five-year extension by the Manchester club, tried 24 players in the match, with Carlos Tevez, Yaya Toure, Vincent Kompany, Pablo Zabaleta and Adam Johnson all in the starting eleven.
But despite that Shaker Nawaf Alabid managed to beat goalkeeper Eirik Johansen with a fierce drive in the 68th minute to seal it for his side.
City have already expressed their desire to bring in more players ahead of the season, and with the unexpected loss they should now be all the more determined to do that.