Last season in the Champions League Manchester City accumulated ten points in what was thought to be a tough group and still failed to qualify.
And it has not got any easier for the Premiership title holders who find themselves in a group with the German, Dutch and Spanish champions.
In their opening game of the champions league campaign they seemed set for a morale boosting three points at Real Madrid until defensive lapses in the final minutes cost them the game.
City have endured a stuttering start to the season conceding 15 goals and lie fourth in the table after a 2-1 success at Fulham at the weekend. Their opponents Borussia Dortmund scored five in their last game and have won three of their opening six Bundesliga matches.
After an encouraging opening in which City through Samir Nasri went close in the first minute, it was Hart who kept his team in the game with a string of fine saves with Mario Gotze, who also hit the woodwork three times, bringing out the best in the England international.
The hosts had their chances but it was giving away possession too easily in midfield which was to prove their undoing.
Just after the hour mark substitute Jack Rodwell gave the ball away for allowing Marco Reus to race clear and score.
The Germans gained confidence and should have doubled their lead but for Hart and some poor finishing.
City were struggling until a controversial penalty gave them a lifeline as Neven Subotic was harshly adjudged to have handled.
Substitute Mario Balotelli kept his cool to stroke home from 12 yards.
So City have now only lost one of their last 35 European home games but Dortmund and their vociferous fans, must be wondering how they failed to take all three points after outplaying the home team.
Referee: Pavel Kralovec (CZE)
Venue: Etihad Stadium
Man City scorers: Balotelli pen 89
Dortmund scorers: Reus 62
Yellow cards: Kompany (MANC), Toure (MANC), Blaszczykowski (DORT)