Disorganisation in defence was to blame for Borussia Dortmund's 3-1 Champions League group stage defeat at Tottenham on Wednesday, says manager Peter Bosz.
Son Heung-min opened the scoring before Harry Kane answered a wonderful Andriy Yarmolenko strike with two goals of his own to claim the decisive victory at Wembley.
Speaking after the match, first-year boss Bosz conceded his side must improve to get a result in Dortmund's next UCL match, against defending champions Real Madrid, in a fortnight's time.
"I am disappointed because we should have got more out of the game," Bosz said. "Above all, we played well in the first half, but were sloppy on two occasions.
"Both teams typically play according to the same philosophy, that is, they want to press high up the pitch and play out from the back.
"We did that very well. We applied pressure far up the pitch, but then the defence needs to be well organised, which wasn't the case when the first goal was scored.
"The goals we conceded were much too soft."
Midfielder Christian Pulisic had a goal called offsides and nearly scored another in the loss. He lamented Dortmund's missed opportunities.
He said: "Tottenham are a very good team. But we had chances, and we really should have got another goal and taken the lead in the first half.
"Unfortunately, it didn't work out that way. We scored a goal which was ruled out due to an offside decision, and then our opponent scored -- and then the game suddenly had a completely different feel to it.
"That is what happened today. Of course we wanted to win against Tottenham. Now the home match is even more significant. We have to beat them at home."