Luciano Spalletti bemoaned a lack of concentration from Inter after they slumped to a 4-1 Serie A defeat at Atalanta on Sunday and missed the chance to move within three points of leaders Juventus.
Inter were battered in a first half in which Atalanta could have put themselves out of sight. Hans Hateboer put the hosts ahead, but Gian Piero Gasperini's side failed to add to the lead in the opening 45 minutes despite having 16 shots on goal.
A controversial penalty, awarded for handball against Gianluca Mancini, allowed Inter to level two minutes after the restart through Mauro Icardi.
However, Mancini enjoyed redemption as he headed Atalanta back in front before Berat Djimsiti and Alejandro Gomez made the points safe, their goals sandwiched by a red card for Inter's Marcelo Brozovic.
"Unfortunately, we seem incapable of maintaining concentration for long periods," Spalletti told DAZN.
"That means we give our opponents extra space and our lapses in focus. We take it too easy and when we're up against a side that is this determined and well-organised, it all becomes more difficult.
16/3 - Atalanta have found one goal with 16 shots attempted in the first half whilst they have scored three goals with the only three shots fired in the second half. Improvement. #AtalantaInter— OptaPaolo (@OptaPaolo) November 11, 2018
"The game was going in the direction we wanted after the equaliser, the direction we had hoped for from the start, but we lost too many individual duels and our positioning was all wrong.
"Atalanta maintained a consistent approach from the start, but we pushed up through the middle and for a while either side could've won.
"Then we had another dip in concentration and Atalanta took advantage on set plays."
On Brozovic's dismissal, which came courtesy of a second yellow card for a rash foul on Josip Ilicic, Spalletti added: "It didn't seem like a nasty foul. At that moment, an emotional reaction can happen."