Real Madrid coach Ancelotti said he understood the fans who supported him and his team during their 5-2 Copa del Rey win over Celta Vigo.
Real beat arch-rivals Barcelona 5-2 last week to throw Celta from two goals down before forcing an extra-time win.
Two late goals, including a penalty from former Chelsea defender Marcos Alonso, made the mood of the crowd clear over 90 minutes.
But Real responded as teenager Endick scored twice in extra time to secure a place in the quarter-finals.
“I see it as a wake-up call from the fans to the team and its coach. It was an acceptable wake-up call after the game against Barcelona. After that, the team responded well,” Ancelotti said.
“The fans booed us and then the team started to complicate a game that we played well on our way to a 2-0 win.
“But then the fans started to push us and we were pushed to the Santiago Bernabeu, which is something very special for us.
“We played well in overtime and managed to win the game, so it was all good in the end.”
Ancelotti was not satisfied with conceding goals and urged his players to focus on the final minutes of the match.
“The tension dropped at the end. “We made two mistakes and allowed our opponents to get back into the game and opened up a game that practically ended with two goals in front,” Ancelotti said.
“We conceded two late goals to the opponent near the end of the game. In the first half, there was a foul on the ball, and the second goal was a result of poor defensive positioning. We played well over 70 minutes.
“Obviously this is impossible. We will have to do more training to avoid these types of mistakes and not lose momentum at the end of the game.”
Real face Las Palmas in La Liga next Sunday afternoon.