Nuri Sahin cited his substitutions as a "mistake" in Borussia Dortmund's 5-2 defeat to Real Madrid in the Champions League on Tuesday. (More Football News)
Donyell Malen and Jamie Gittens had given the Bundesliga side a two-goal advantage heading into half-time, but they were unable to hold on to their lead.
Madrid came out firing after the interval, with a hat-trick from Vinicius Junior along with goals from Antonio Rudiger and Lucas Vazquez sealing the triumph.
But Sahin's decision to replace both Malen and Gittens for defender Waldemar Anton and holding midfielder Pascal Gross proved to be Dortmund's undoing.
Five minutes after Gittens' substitution, Madrid halved the deficit through Rudiger, and were level 105 seconds later when Vinicius struck beyond Gregor Kobel.
"It's not easy to explain, of course. We, who I thought played well with the ball, really had a lot of solutions," Sahin said.
"The boys did well, scored two goals and then went into half-time and we knew it would be very long. The second half very, very long.
"We noticed in the second half that we were being pushed back, we had defensive problems and I thought we should go to the three-man defence, and that didn't work out for us.
"It's my mistake and I have to live with it. There will be criticism, but that's something I have to face.
"We defended very, very badly. But also we have to factor the individual class of Real, a complete team."
However, Sahin insisted his side can take positives from the way they played in the first 45 minutes at the Bernabeu.
Dortmund registered six shots, with five of those on target, entering the interval with an expected goals (xG) total of 1.49 compared to Los Blancos' 1.14.
The visitors also boasted 52% possession, while also playing 158 passes in the opposition half to Madrid's 133 in the first half.
"It's an extremely bitter loss today, it hurts because we go out with the feeling that it was possible to go out with a better result," Sahin said.
"But tomorrow we also have to take the positives from this game with us.
"If we can play football like this against Real Madrid, then we have to do it against everyone and that has to be our benchmark. We're doing well up front."
