Tottenham manager Mauricio Pochettino rued a missed opportunity as his side lost 2-1 to Monaco in the Champions League on Wednesday.
Spurs suffered a disappointing defeat in front of a record crowd as they started their campaign at their temporary European home of Wembley.
Monaco went ahead after just 15 minutes through Bernardo Silva and they doubled that on 31 when Thomas Lemar found the back of the net.
Toby Alderweireld pulled one back on the stroke of half-time but the home side could not draw level in the second half.
Speaking after the game, Pochettino said: "I think that we all agree that we started well but then we conceded after 15 minutes.
"We cannot concede in that way at this level, in the Premier League, the Champions League. It is difficult to accept how we conceded a goal in this way.
"When you concede like this it is very difficult.
"It is true that we had more chances, our positions, we were better than Monaco but they were more effective.
"Today was an opportunity to give to our fans a good victory and it is a shame for our fans."
The Spurs boss, who had never lost a European game at home with Tottenham before Wednesday, described his side as having a "lack of passion".
He said: " I was speaking with my players at half-time.
"I think we needed more control in the centre of midfield, we needed to move Dele Alli up the pitch to be more aggressive.
"It is not new. I think we were better than Monaco, we need to win games, we need to be more aggressive with the ball.
"We need to play the way we are meant to play. They played in a very comfortable position.
"It is a fantastic opportunity, we have worked hard to be here and we need to be better.
"We need to work more on being aggressive, to show we are hungry on the pitch. In the second half I think we started well, but not well enough."
Monaco manager Leonardo Jardim admitted he used their 2-1 win at Arsenal in last season's Champions League when preparing for the game against Spurs.
Nabil Dirar was forced off just five minutes into the game due to injury and whilst it was not part of the plan to change players until the second half, the Monaco boss admits it worked out well with Dirar's replacement Lemar on the scoresheet.
Jardim said: "We tried to think back to when we won against Arsenal at the Emirates, similar surroundings and size (of stadium), so that is what we used going into the game.
"The players loved to play in a huge full stadium. I think the size of the pitch affected Tottenham more than it did us.
"We will have a look at (Dirar) tonight (to assess the level of injury).
"It did upset us tactically, we didn't want to make such an early substitution.
"We wanted to keep our substitutions until later but it was a happy sub in the end because he scored the second goal so it all worked out well for us."
Source: PA
