Tottenham failed to advance in the NextGen series as an awful goalkeeping display from Lawrence Vigouroux helped Sporting CP come away 5-3 victors after extra-time at the Matchroom Stadium.
Alberto Coelho was the main benefactor of the Frenchman's disastrous showing, scoring twice while also winning a penalty from the keeper.
Spurs brought in midfielders Laste Dombaxe and Nathan Oduwa after overcoming Paris Saint-Germain in the last round while Sporting made three changes to the side that comfortably disposed of Liverpool.
The first sign of Vigouroux’s calamitous evening came when an early defensive mix-up saw him clatter into Coelho, one of the Sporting changes, with the ricocheted ball bouncing wide.
On six minutes however the visitors were ahead. A long ball was beautifully brought down by Coelho who then produced an exquisite lob that looped into the net.
Within two minutes, the English side were level. After Sporting failed to deal with a corner, 16-year-old Nathan Oduwa rammed the ball home on his left-foot for the equaliser.
Spurs were suddenly in the ascendancy and could have gone in front when Mickael Meira had to twice save smartly from Kenny McEvoy.
The Lillywhites were made to pay for their profligacy when Sporting went ahead on 19 minutes. Spurs skipper Kevin Stewart found Ricardo Esgagio simply too hot to handle on the right wing and his cross was perfectly weighted for the onrushing Coelho to stab home.
Sporting nearly had a third when Vigouroux hastily misjudged a bouncing ball and was left grateful that Iuri Medieoros could only find the side-netting.
The 19-year-old was certainly not having the best of nights and was at fault again when with the ball safely in his hands, he bizarrely gifted it straight to Coelho, whose lay off was cheekily chipped wide by Farley Rosa.
However, Vigouroux’s nightmare continued as he again misjudged a simple ball over the top before clumsily felling Joao Palhinha, who had beaten him to the ball. Central-defender Ruben Semedo made no mistake from the spot.
That save proved to be decisive as with 10 minutes to play, the impressive Shaquile Coulthirst was cynically brown down for a penalty, which was coolly dispatched by Dombaxe. That seemed to be that but in the very last seconds, Meira made his first mistake of the evening as he fumbled and allowed substitute Roman Michael-Percil to lash home the equaliser.
However, in came Vigouroux once more as minutes into extra-time he allowed a tame Alexandre Guedes shot to trickle in at his near-post to put Sporting ahead again.
The Portuguese youngsters put the result beyond doubt when the monstrous Atud Fobokoo lashed home the goal of the evening from all of 40 yards past a despairing Vigouroux.