Genoa plunged Inter further into crisis with Goran Pandev punishing his old club, while Eugenio Lamanna saved a late Antonio Candreva penalty.
The Grifone risked being sucked back into the relegation zone after one point from six rounds, but got back on track with this unexpected success story.
Pandev got the only goal of the game, netting the rebound after Miguel Veloso’s screamer was fingertipped on to the crossbar.
Candreva had the chance to equalise late on, but Lamanna confirmed his status as a spot-kick specialist by saving the penalty.
Geoffrey Kondogbia saw red for dissent and Inter can wave goodbye to Europe.
Or see how all today’s games unfolded on the Liveblog.