Thomas Tuchel has labelled Borussia Dortmund's record-breaking 8-4 Champions League victory over Legia Warsaw as "surreal".
Marco Reus - making his first start of the season after recovering from injury - helped to set a new Champions League record for the number of goals scored in one match when he sealed his hat-trick in second-half stoppage time on Tuesday.
Dortmund & Legia make CL history
And Tuchel, whose side sit top of Group F with a two-point cushion over European champions Real Madrid, has promised to address Dortmund's defensive issues.
"Apparently there has never been such a thing, so it is also difficult to analyse this game," Tuchel told the club's official website.
"It was surreal, I have never seen anything like that before. We left so much space in the defence, and we've got a lot of trouble with it.
"Many mistakes were made by us. In the end, we managed to win. I am sorry for Roman Weidenfeller. The blatant mistakes that we have made, I will address."
One major positive for Tuchel was the performance of Reus, who had not featured since picking up a groin injury at the end of last season.
Dortmund's Reus revels in return
"It is fantastic that Marco worked so well today. The game was not so intense that I would have to [substitute] him," Tuchel added.
"We had to wait a long time, much too long. It was an amazing comeback from him."
Dortmund face Madrid at the Santiago Bernabeu on December 7 in a game that will decide the winner of Group F.