Tottenham conceded two goals in injury time to slip to a 2-0 Champions League defeat at Sporting Lisbon.
Spurs were contemplating an evening of frustration as it looked like they would be held to a 0-0 draw in Portugal before things went very wrong at the death.
Paulinho nodded home from a corner and then with virtually the last kick Arthur Gomes sauntered into the box to convert and put Sporting top of Group D with two wins from two.
Boss Antonio Conte will be furious with the manner of the loss as his side suffered their first defeat since April in an uninspiring display.
It had been a slow start, with Marcus Edwards intent on showing his old club what they were missing from the start.
And after a darting run down the channel he laid a chance on for Pedro Goncalves inside the opening 10 minutes, but Hugo Lloris was equal to the low shot and tipped it wide.
Spurs looked threatening in patches and thought they took the lead on the stroke of half-time as Richarlison rounded the goalkeeper after being played through by Harry Kane, but the Brazilian was well offside.
It needed another Lloris save to ensure the visitors went in level as the Frenchman denied Edwards a wonder goal.
The 23-year-old, who Mauricio Pochettino once compared to Lionel Messi, sauntered past a number of challenges to advance into the box, played a one-two, beat another man and then stabbed a shot, but was denied by a fine low stop from the Frenchman.
Spurs started the second half strongly and had enough chances to take control of the game.
Emerson Royal could not connect properly with Kane’s quick free-kick, the England captain then stung the palms of Antonio Adan and Richarlison drifted an effort wide at the far post.
Spurs upped the ante in search of the breakthrough and Kane was just unable to get on the end of a wicked Ivan Perisic cross while Richarlison headed Dejan Kulusevski’s cross wide.
But Spurs were undone in three minutes of injury time.
Paulinho glanced a header home before Arthur produced a moment of brilliance to weave into the area and shoot under Lloris.