Frank de Boer's Inter reign suffered another early setback as Hapoel Be'er Sheva won 2-0 at San Siro in their Europa League Group K opener.
The three-time European champions have won just one of their first three Serie A games under the Dutchman, with goals from Miguel Vitor and Maor Buzaglo ensuring an equally miserable start to their continental campaign.
Far from being a smash-and-grab, though, this was a thoroughly deserved triumph for the Israeli champions, who could have led long before their two goals, which both came in the second half.
Eder struck a post in Inter's best moment, but any hope that last weekend's victory at Pescara would kickstart De Boer's tenure was quickly extinguished by a home performance that got progressively worse as the match wore on and saw them produce only three shots on target.
Captain Mauro Icardi had bagged all three of his team's prior goals this season, and the Milan outfit looked predictably toothless as he started the match on the bench.
Struggling Inter now turn their attention to a daunting meeting with Serie A champions Juventus on Sunday.
Though Be'er Sheva came into the game winless in their last five European away matches, it was they who started the brighter and should have taken an early lead.
Buzaglo's centre from the right found Lucio Maranhao completely unmarked, but he directed his header wide with Samir Handanovic rooted to the spot.
Inter, having made seven changes to a winning side, could not match the aggressive tempo of their busy visitors, who squandered another headed chance as Buzaglo stretched onto Ben Bitton's cross.
Handanovic was soon called into action for the first time, blocking Maranhao's drive after Ovidiu Hoban had sent him clear of the hosts' creaking back-line.
Inter finally forged a first sight of goal shortly before half-time and were so nearly rewarded. Yuto Nagatomo's delivery from the left skipped through the penalty area to the far side, where Eder steadied himself before rattling a shot against the post.
Eder zipped another effort wide at the start of the second period, but a dreary display was belatedly punished in the 54th minute.
A smart free-kick routine saw Buzaglo slip Maranhao in on the right, and his low ball across the face of goal was met by defender Vitor with a clinical finish to stun the San Siro crowd.
Be'er Sheva were not finished there, either. Handanovic stood up to beat away Buzaglo's blast and then blocked Maranhao's shot at his near post as the Brazilian again wreaked havoc.
Their next attempt was dragged off target by Tony Nwakaeme, before Hoban's swaying strike dipped wide on the opposite side.
Another set-piece would result in another goal, though. This time Buzaglo went direct from the free-kick, around 25 yards out, and curled magnificently into the near top corner with 21 minutes remaining.
Icardi was summoned from the bench, but even his presence could not provide Inter any relief and Be'er Sheva instead coasted to victory, with Bitton even clipping the bar with a fine late lob.