Mauricio Pochettino backing for Dele Alli

Alli was sent off as Tottenham were held to a 2-2 draw against Gent at Wembley, which meant Pochettino's men lost the tie 3-2 on aggregate and crashed out in the last 32 of the Europa League.

Harry Kane's own goal had cancelled out Christian Eriksen's early opener before Alli's moment of madness came in the 39th minute.

The 20-year-old, frustrated at being denied a free-kick, jumped to his feet, miscontrolled the ball and then thrust his right foot high and into the shin of Gent's Brecht Dejaegere.

It meant Tottenham were left needing to score twice more with 10 men and while Victor Wanyama gave the hosts temporary hope in the second half, Jeremy Perbet's late goal sealed Gent a surprise victory.

"He is very disappointed and sad," Pochettino said of Alli. "In football, it happens. He knows he made a mistake. Now he tries to move on and improve. In the future we must avoid that situation.

"It's difficult. It's not to justify him but it's a different action, he was fouled before, it was an action that was a clear foul. That's not to blame the referee but the action came in very soon, that tackle, and I think he deserved to be sent off. He knows. But that kind of action can always happen.

"It's only one and a half years he is playing for Tottenham in the Premier League, all that he achieved in a very short period is because he is special and a special boy.

"He has unbelievable personality and character. But before that he is a great player.

"In the same way, he is how he is. He is very passionate to play football and sometimes this action happens. Now it's time to support him, he is very sad and disappointed in the changing room."

It is not the first time Alli has fallen foul of the law.

He was lucky to escape punishment for kicking out at Fiorentina defender Nenad Tomovic in the Europa League last year and was banned for three matches in April after punching West Brom's Claudio Yacob in the Premier League.

Former Tottenham manager Harry Redknapp believes Alli was lucky not to cause Dejaegere serious damage.

"[Alli] could have finished a fella's career. He could have finished a boy's career. There's no doubt. It was that bad," Redknapp said on BT Sport.

"He could have broken the lad's leg, snapped his leg, and that would have been the end."He's got to cut that out of his game. He's got that streak in him. I rave about the boy but that tackle is horrendous.

"Alli's challenge was also criticised by former Tottenham midfielder and manager Glenn Hoddle.

"It's undefendable," Hoddle said. 

"You can't defend that. It was a reaction, a poor reaction to losing the ball, not getting the foul. You can't do that on a football pitch. Not nowadays.

Tottenham's defeat means they have now failed to go past the quarter-finals of the Europa League, or its equivalent UEFA Cup, in any of their nine attempts in the last 10 years.

Any chance of silverware would now appear to rest solely on the FA Cup, where Spurs play Millwall in the last eight.

They take on Stoke at White Hart Lane on Sunday, looking to reduce a 10-point gap on Premier League leaders Chelsea.

"It's key now to recover physcially and mentally," Pochettino said.

"On Sunday a team that is very fresh arrives. Be sure they will be ready to fight against us.

"Now we move on and forget this competition. We try to be focused on Sunday and be ready to fight because the competition doesn't wait for you, the competition pushes you to try to give your best.

"Now is not time to cry, it is time to move on.

"Gent were on the back foot for most of the contest but they had done their damage in the first leg last week and played an effective counter-attacking game.

"I should apologise but if you qualify do you have to apologise, that is the question," Gent boss Hein Vanhaezebrouck said.

"Today we were not good but we cannot forget the first game because that made the difference. That was when we played our game. If Tottenham lost this one, it wasn't here, it was in Gent."

Vanhaezebrouck also felt no bitterness towards Alli.

"I don't think he did it on purpose but it was a red card, it was really dangerous," Vanhaezebrouck said.

"It is unlucky but I would not blame the guy."