Tottenham were denied a place in the last 16 of the Champions League as Harry Kane's strike deep into stoppage time was ruled out after a VAR review in a 1-1 draw with Sporting Lisbon on Wednesday.
Spurs now still need at least a point when they travel to Marseille on Tuesday to reach the knockout phase with all four sides in Group D still alive heading into matchday six.
A draw will also be enough for Sporting to go through when they host Eintracht Frankfurt.
Spurs will most likely have to cope without coach Antonio Conte on the sidelines in southern France after the Italian was shown a red card in a controversial finale.
Tottenham had been forced the come from behind after ex-Spurs forward Marcus Edwards opened the scoring for Sporting.
Rodrigo Bentancur levelled 10 minutes from time and the home side thought they had snatched victory at the death when Kane smashed in from a narrow angle.
But after a VAR check lasting over three minutes, Kane was adjudged to have been offside from Emerson Royal's header.
A point was the least that Sporting deserved after enjoying the better of the chances until the closing stages.
Conte has called on the Spurs' board to further strengthen his squad in the January transfer window after back-to-back defeats dampened their bright start to the Premier League season.
However, it was a Tottenham academy graduate discarded by the club at a young age that was the star of the opening 45 minutes.
Edwards made just one appearance for his boyhood club before leaving to make his career in Portugal, firstly with Vitoria Guimaraes, before making the move to Sporting and came back to haunt his old club with a fine strike into the bottom corner on 22 minutes.
Spurs have badly missed the creativity of Dejan Kulusevki and goal threat of Richarlison in recent weeks through injury.
As the hosts laboured to find a way back into the game, Sporting should have been out of sight.
Hugo Lloris made amends for any questions over his positioning for the opening goal to save a one-on-one with Flavio Nazinho.
Moments later Nazinho slotted wide with the goal gaping after Lloris parried Pedro Porro's initial effort.
Sporting boss Ruben Amorim soon had his head in his hands as Bentancur outjumped goalkeeper Antonio Adan to head in Ivan Perisic's corner.
Eric Dier then should have followed Edwards' lead to come to haunt his former club.
Twice the England defender headed wide glorious chances from point-blank range.
Sporting had kept Harry Kane and Son Heung-min quiet for the 90 minutes but the England captain thought he had won the game in stoppage time.
As tension mounted during the wait for the goal to be reviewed, Conte exploded at Dutch referee Danny Makkelie when offside was given, leaving Tottenham with work to do in Marseille in six days' time.