Manager Carlo Ancelotti took responsibility for Real Madrid's 4-0 El Clasico thrashing by Barcelona on Sunday, saying the defeat was "my fault."
Pierre-Emerick Aubameyang scored twice and Ronald Araujo and Ferran Torres were also on the scoresheet as Barca recorded their biggest Clasico win at the Bernabeu since 2015.
Aubameyang, Torres and Ousmane Dembele -- who provided two assists -- all spurned second-half chances to increase the margin of Barca's victory.
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The result left Madrid, who hadn't lost in LaLiga since Jan. 2, nine points clear at the top of the table, with Barca 12 points behind in third place.
"It isn't difficult to explain. They played better than us," Ancelotti told Movistar. "We wanted to control the ball more, to press them high, but it didn't work ... It's my fault."
He added: "We weren't recognisable. Everything went badly. We have to forget it and look forward, we have a big lead [in the table]. I said [to the players] that it was the coach's fault."
With top scorer Karim Benzema absent with a calf injury, Ancelotti picked Luka Modric in an unfamiliar forward role, while Nacho Fernandez struggled as a left-back replacement for Ferland Mendy.
"It was one of our worst games of the season," Nacho said. "Maybe we relaxed with our lead in the table, and it wasn't a game to do that, quite the opposite. It always hurts to lose a Clasico but we've had a great season until now."
Added Ancelotti: "The plan with Modric was to try to play the ball out from the back and find space between the lines with Rodrygo, [Federico] Valverde and Vinicius. It didn't work. It isn't a problem for me to take responsibility. Sometimes you get it right and sometimes you don't. I failed."
Goalkeeper Thibaut Courtois said the display was "unacceptable."
"We wanted to start with intensity, but they found spaces. We weren't compact," he told Movistar. "We have to talk about the tactics internally. It didn't work, what we did from the start of the game, or in the second half ... They had chances. The result could have been much worse."
Ancelotti called for "balance" in an assessment of the team's performance, denying that such a heavy defeat would affect the players' morale long-term.
"We'd have taken this at the start of the season, being nine points ahead and in the Champions League quarterfinals on March 20," he said. "I'm really sorry and I'm very sad, but the nine points give me balance."
Real Madrid will face Celta Vigo in LaLiga after the international break, before the first leg of their Champions League quarterfinal with Chelsea on April 6.