Two late goals flattened Tottenham as Inter Milan came from a goal down to win their Champions League Group B opener 2-1 at the San Siro.
Spurs were ahead early in the second half after Christian Eriksen's deflected volley had looped in (53), only for Mauro Icardi to hit a sensational volley to level things up (86).
And as Inter piled on the pressure late on, Matias Vecino nodded home a stoppage-time winner as Inter returned to Europe's top table with a dramatic win.
Inter Milan: Handanovic (8), Skriniar (6), De Vrij (7), Miranda (6), Asamoah (6), Vecino (7), Brozovic (6), Politano (7), Nainggolan (6), Perisic (6), Icardi (7)
Subs: Candreva (6), Keita (5), Valero (NA)
Tottenham: Vorm (6), Aurier (7), Sanchez (6), Vertonghen (6), Davies (5), Dier (5), Dembele (7), Lamela (6), Eriksen (7), Son (5), Kane (7)
Subs: Lucas (7), Winks (5), Rose (NA)
Man of the match: Samir Handanovic
The result means Tottenham's mini-rot goes on, as they suffer their third straight defeat for the first time under Mauricio Pochettino.
Spurs looked nervy early on as Inter players and fans were energised by a first Champions League appearance since 2011, but the best chance of the first half did fall to the visitors.
Picking up Eriksen's superb lofted ball into the box, Harry Kane's first touch was perfect, but his second pushed him wide and out of play as he looked to round goalkeeper Samir Handanovic from 10 yards.
But Eriksen put Spurs ahead eight minutes after the break, seeing a long-range effort beaten away by Handanovic before his return half-volley looped over the goalkeeper via a deflection off Miranda.
There were five changes for Spurs in Milan; Aurier, Sanchez, Davies, Lamela and Son came in to replace Trippier, Alderweireld, Rose, Winks and Lucas. Alli and Lloris were out injured, while Trippier and Alderweireld were left at home for "technical reasons."
Erik Lamela tested Handanovic on three occasions after the opener, but the Slovenian stopper was equal to them as Spurs looked more comfortable heading into the final stages.
Substitute Lucas Moura caused problems, and Kane held the ball up well for the visitors, but they were stunned by Icardi's sensational leveller with four minutes remaining.
Running onto Kwadwo Asamoah's cut-back from the left, Icardi struck a first-time volley into the bottom left corner from 25 yards on his Champions League debut.
Inter pressed in the final stages, and got their winner in the 92nd minute through Vecino, heading home from six yards after Stefan de Vrij had nodded his own header back across goal from a corner.
The pundit - Ryan Mason
"The debate (about whether or not Kane needs a rest) won't stop until he starts scoring. He had one really good opportunity.
"He took a great first touch and could have dinked it over the 'keeper but he opted to go round him, lost his balance and the ball got stuck under his feet. He'll have been disappointed. I think a fully fit, confident Harry Kane would have taken that chance."
Man of the match - Samir Handanovic
Though he may have done better with Eriksen's opener, Handanovic made three vital stops from Lamela in the second half to keep the hosts in the game.
He made five stops overall, and was dominant aerially as Tottenham looked for a two-goal cushion.
- Tottenham have won just one of their previous 10 European matches away from home against Italian opposition (D4 L5).
- Inter Milan forward Mauro Icardi has scored in each of his last three appearances in European competition, after scoring just one in his previous 11 games.
- Inter Milan have won four of their last five Champions League matches against English teams (L1 - vs Spurs).
- Tottenham's Christian Eriksen has scored three goals in his last five Champions League appearances, one more than he netted in his previous 24 in the competition (2 goals).
Tottenham now go to Brighton in the Premier League on Saturday at 5.30pm, while Inter are at Sampdoria in Serie A at 7.30pm on Saturday night.