Mauricio Pochettino has taken responsibility for Tottenham's 1-0 defeat to Ajax, admitting he selected the wrong formation in the Champions League semi-final first leg.
With Pochettino opting to field a three-man defence, Donny van de Beek grabbed an early goal to secure a precious 1-0 victory at Tottenham in the first leg of their Champions League semi-final on Tuesday.
The 22-year-old struck in the 15th minute to give Ajax a crucial away goal and leave Spurs facing a daunting task in Amsterdam if they are to reach the final for the first time.
When asked if he had any regrets about fielding Davinson Sanchez, Toby Alderweireld and Jan Vertonghen as a back three, Pochettino told BT Sport:
" Watching now of course 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 our lack of intensity and aggression which is why we conceded the goal, not our shape. I take responsibility. Ajax have the advantage but it is still open."
Ajax, having already knocked out Real Madrid and Juventus en route to their first semi-final in Europe's elite competition since 1997, were too pacey for a labouring home side, especially in a first half in which they could have put the tie to bed.
Tottenham did improve after the break but Ajax defended their lead diligently to restrict the home attack and almost scored a second goal late on when David Neres hit the post.
Only one of the 17 previous teams to lose the first leg at home in a European Cup/Champions League semi-final tie has progressed into the final - Ajax in 1995-96.
Pochettino added: "I think the first half we started not in a good way. My feeling is that they were more reactive and it was difficult for us to play.
"It was our lack of energy that made our game difficult. We conceded a goal but then we started to build into the game.
"Sissoko provided the team with good energy and we started to play in the way we wanted to from the beginning.
"We started to push them and it was an even game in the second half. We're alive and we need to believe we can go there and win the game."