Gian Piero Gasperini bemoaned his side's bad luck after Champions League stand-ins Trabzonspor sent the Nerazzurri crashing to their third straight defeat.
Ondrej Celustka's late goal sent the 2010 European champions to an embarrassing defeat that will heap yet more presure on their beleaguered coach.
Under Gasperini Inter have now lost to Milan in the Italian Super Cup, Palermo in Serie A and now the Turkish side, who are only in the competition as a replacement for Fenerbahce.
But the coach is hoping this latest reverse will provoke a reaction. He told Sky Sport Italia: ''Even though this defeat leaves a lot of regret, the team gave a lot and there were some strong performances individually. We're unlucky at the moment. When it rains, it pours.
''The reaction was anger and wanting to fight back, as this is a strong squad and showed what grit it played with. In football these moments can happen and must give us the fire to get back on track.''
Gasperini put his much talked about 4-3-3 formation on hold and played with a traditional back four at the San Siro, and later insisted he hadn't been pressurised to do so by president Massimo Moratti.
He added: ''This story about President Moratti pressuring me is not true. He has always been very supportive towards me. We discuss things, but don't make it look as if it's something that it's not.
''The Palermo defeat sparked a great deal of criticism that was exaggerated. This was an important lesson tonight, as we improved considerably and can do far better.
''We started just two days before the season kicked off, so there are problems in gelling the side, but nobody can doubt our effort.
''Paradoxically, this could prove to be a very important defeat to spark a reaction in the side. This is a very solid, positive and united squad.
''On the field we need to find the right balance. There have been steps forward, but we need more.''
Julio Cesar said a post-mortem would be needed after Inter's defeat. He said: "We have to talk things over between ourselves. It is a difficult moment, but we have to stay united and work together to find the right path.
"We did not expect a defeat like this, but it happened and now we have to find our way out of this situation. At times like this, we have to talk things over between ourselves and understand what we are missing so we can find the right path forward.
"It's not about finding the guilty party or pointing the finger of blame. We just have to work."