Borussia Monchengladbach coach Andre Schubert felt his team lost focus in their 2-1 Champions League defeat to Manchester City.
On their first home match in Europe's top competition for 30 years, Monchengladbach took a deserved 54th minute lead through Lars Stindl.
They would have been ahead long before but for a string of fine saves from Joe Hart - most notably when the England goalkeeper kept out Raffael's first-half penalty.
Nicolas Otamendi levelled for Cityin the 65th minute - a goal eventually credited Andreas Christensen - and the visitors asserted themselves from that point on, with Sergio Aguero winning and converting a 90th-minute penalty to cruelly leave Monchengladbach with two defeats from their opening Group D games.
"We are very disappointed," Schubert told reporters.
"We have worked very hard, but we played against a top European team.
"The penalty against us in the last minute was also down to a lack of focus.
"Our performance was really strong, so the outcome of the game is naturally very bitter."
