The England midfielder was dismissed for a lunging tackle on Brecht Dejaegere during the first half of his side's last-32 clash with the Belgian outfit.
With the game level at 1-1 at the time, but Spurs behind on aggregate, Alli lost possession before planting his foot just below Dejaegere's knee, leaving referee Manuel de Sousa no choice but to send him off.
Mauricio Pochettino's side would go on to draw the game 2-2, meaning they were dumped out of the competition on by a 3-2 aggregate scoreline.
And UEFA have now announced the punishment that will be dished out to Dele, who will now miss three matches of Tottenham's next venture into European competition.
That, of course, looks almost certain to be the 2017-18 Champions League, with Tottenham well on course to finish in the top four where they're currently second place, two points ahead of Manchester City in third.
Spurs are on a six-game unbeaten run in all competitions, with their last defeat having come in the away leg of their Europa League tie with Gent.