Mauricio Pochettino had hope that Tottenham could overturn their 1-0 deficit against Ajax in the second leg.
"It's going to be difficult, but it's still open. It's about preparing for the second leg. We will try to win. It will be tough for us, but also tough for them," said the Argentine.
Pochettino admitted that he got his tactics wrong early in going to a 3 defender backline.
"I can accept it was a mistake, the shape we used. But there were not too many options. I am not happy - you cannot guess what happens if we play in a different way. It was the not the shape that conceded the goal. Our approach to the game was not good. I am the manager so I have responsibility."