Internazionale head coach Stefano Pioli has lambasted his side following their Europa League group stage exit on Thursday evening.
The Nerazzurri held a two-goal lead before succuming to Israeli side Hapoel Be-er Sheva 3-2 at the Turner Stadium.
Captain Mauro Icardi got the scoring underway after just 12 minutes, in what was supposed to be a comfortbale evening for the Serie A giants.
Marceloa Brozovic added a second for Inter before a second-half capitualtion, where Lucio Maranhao first pullled a goal back before goalkeeper Samir Handanovic was punished with a red card.
Anthony Nwakaeme converted the subsequent spot-kick before former Chelsea striker Ben Sahar grabbed the stoppage time winner.
Pioli, who recently replaced Frank de Boer in the Inter hot-seat, was honest in his opinion following the shock result, citing his side's mentality this season as a reason for their recent results.
"We stopped playing as a team and were presumptuous," he said after the game. "That should never happen and we cannot afford to do that if we want to win games.
"We had the chance to go 3-0 up and didn't take it. We must work hard to ensure we don't keep giving away certain opportunities.
"We cannot play such a two-faced match. In the first half we did really well, badly in the second. All we needed to do was maintain that attitude.
"In fitness terms we're ok, as we pushed at the end. What matters here is the mentality and we must improve," Pioli added.
"The past no longer counts, what matters is the present and we cannot be satisfied with our work. We are working on all fronts: physical, psychological and tactical. A team that plays that well in the first half cannot offer a second-half performance like that.
"Inter have players of great quality, but we need to know how to suffer under pressure. The performance was not worthy of Inter. We got too deep and allowed Hapoel back into the game. I changed a few things, trying to recover the balance that we had lost."