Xavi's overhaul of Barca took another huge step as they humbled the La Liga leaders at the Bernabeu largely thanks to January signings Pierre-Emerick Aubameyang and Ferran Torres.

Aubameyang broke the deadlock when he headed in Ousmane Dembele's cross with 29 minutes gone before Ronald Araujo nodded in from a corner to double the lead.

Two minutes into the second half, Barca hit Madrid on the break, with the move capped when Aubameyang's flick was met by a first-time shot from Torres.

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Torres then returned the favour four minutes later as Aubameyang dinked a shot over Thibaut Courtois, with VAR awarding the goal after the offside flag had gone up.

Sevilla could not take full advantage of Madrid's defeat as they were held to a goalless draw by Real Sociedad - a third straight draw for the second-placed side and seventh in their last nine.

But the Spanish papers on Monday morning were dominated by the fallout to events at the Bernabeu. Marca ran the headline "a slap that hurts" with Real described as "unrecognised" despite Thibaut Courtois' best efforts.

AS lead with "black night", with Xavi's side now "fantasising" of La Liga after "destroying the worst Madrid".

Analysis: Are Barcelona back?

Spanish football expert Alvaro Montero told Sky Sports:

"Gerard Pique took to Twitter last night and wrote in English, 'we are back' and it seems that Barcelona are. It was only fair to then ask Xavi if he felt the same way and he said that maybe we are, but perhaps not enough to win La Liga this season. They have had two difficult years with Lionel Messi wanting to leave and then eventually leaving, and then the lack of titles.

"No La Liga trophy and no Champions League success has been followed by playing in the Europa League. 4-0 is maybe not enough to make a title race of this as they are still 12 points behind Madrid despite having a game in hand. It seems that it's an important moment for the club.

"Pierre-Emerick Aubameyang has made a key impact. In Barcelona, it is rare for a player have such an influence coming in during the January transfer window. The last player to have such an impact was Edgar Davids. He's scored seven goals in seven games in La Liga and was also important against Galatasaray and Napoli.

"Ronaldo Koeman didn't have this type of player. He had to rely on Memphis Depay who has different qualities but not the scoring ability of Aubameyang."

Courtois: We gave an unacceptable image of this club

Thibaut Courtois slammed his team-mates after their thrashing.

Los Blancos were missing some key players including Karim Benzema, but had more time to prepare for the game as Barcelona played away at Galatasaray in the Europa League on Thursday.

After the game, Courtois told Spanish television channel Movistar, as per Sport: "Today we gave an unacceptable image for this club. There are players missing, but you didn't notice that it was them that played Thursday (in Istanbul).

"They found a lot of space. We weren't compact and weren't able to keep the goals out. For the first goal, they anticipate better at the front post and we're not switched on for the second either.

"After the break, we think we can come back, and after 10 seconds Ferran Torres is one on one with me."

Courtois also questioned the tactics of Ancelotti, referring to the last time Real Madrid played with a false nine - which was in their 1-0 Copa del Rey exit to Athletic Bilbao last month.

He said: "We will have to talk about the tactics internally. They haven't worked at the start of the game or the second half, we have to discuss it internally, not here.

"We played with a false nine in the Copa and hardly had any shots and it was the same here. We started okay, we had a chance with Fede Valverde which Marc ter Stegen saved well, but from there we dropped off.

"We didn't find the free man playing out and that makes it hard. Then in the second half, we cannot start like that. This badge demands that you fight and in the second half we did not. We could have lost by even more."

Xavi: We could have scored even more

After his Barcelona side produced a first Clasico victory in seven attempts - they had lost their last five meetings, Xavi Hernandez said: "We're very happy, very satisfied for all the Barca supporters.

"The meaning of this victory, I think it can change, more or less, the dynamics of the present and also of the future. That's the first thing I want to say. As far as the game, we had understood that (Luka) Modric and (Toni) Kroos were out, and we looked for the backs of the interior players of Real Madrid.

"(David) Alaba was also jumping on Frenkie (de Jong), and then Ousmane (Dembele) was one against one. We have shown a lot of personality. I asked the players, I told them it was a game to have a lot of personality, to be bold, not to lose the ball.

It was Real's first home defeat of the season, in the midst of their 120th anniversary celebrations.

Xavi added: "I asked them not to lose any silly balls, because that's what Madrid takes advantage of, and we have reinforced it with the transitions and (Ronald) Araujo defending Vinicius . So the game has been under control. We have been in control with (Pierre-Emerick) Aubameyang.

"We have understood that we have to read between the lines. We have recovered many balls from the opposition. We have created many chances with attacking moves. I think we have been far superior to Real Madrid and we could have scored even more goals.

"It's very difficult to win 4-0 at the Bernabeu playing so well, and I'm very happy for the players, because some of them were going through difficult times in their careers. They were criticised and judged, and today they have proved they are wonderful players.

"They have personalities, they are bold, and this is the way forward. As a coach I am new, and winning 4-0 at the Bernabeu reinforces my role. It reinforces the project, the idea of the game, the model of the game we want to follow. We have no doubt that Barca should compete playing the way we have played tonight."

Ancelotti takes responsibility for thrashing

Carlo Ancelotti took responsibility after Real's four-game winning run in La Liga came to an emphatic end.

"My strategy has not been good. It didn't get a very good result. I don't know, that's all. I have not made a good strategy in trying to defeat Barca. Barca have played better than we have played and they deserved the victory.

"It's not a problem to take on the responsibility, because I didn't prepare for the game correctly. Sometimes you do it correctly, sometimes you don't.

"I failed in this game, but I'm not making a drama out of it. It's a defeat, yes. We know how important it is to win a game against Barca, especially for the supporters. We are very sorry, but we have to keep working, move forward and to prepare our game over the next couple of weeks.

"We should keep calm and stay balanced, because of course, we are very down after this defeat, but we have to think that we have nine points advantage (over Sevilla at the top of the standings). We should be calm and keep calm."

Busquets: We will go for the league

Sergio Busquets says Barcelona 'will go for' the La Liga title. With Barcelona now up to third in the league, the club captain has claimed they will remain in pursuit of their rivals Madrid.

Speaking to Barca TV, Busquets said: "Today I think everything worked out for us, I think we could have scored many more goals today. Look, we knew if we did things properly today we would win. That's what we've been doing with this coach.

"We could have scored more goals. If we have the slightest chance in the league we will go for it, it is difficult but we must be prepared in case points are left. First you have to put yourself in second place, because Sevilla is there.

"In the last Clásico we played under Xavi we also had control and possession but they did much more damage to us on the counterattack and today we controlled it very well."

Aubameyang shows life after Arsenal

Pierre-Emerick Aubameyang has reignited his career since joining Barcelona from Arsenal.

The Gabon forward has scored nine goals in all competitions since making the switch in January.

Asked if they can push for the title, Aubameyang said: "We'll see where we can go from here after this big victory. I was very excited to come to Barcelona and do well. It's very easy when you play with such good players."

What's next?

Real Madrid are back in action after the international break with a trip to Celta Vigo on April 2 (5.30pm kick off) before facing Chelsea in their Champions League quarter final first-leg four days later, while Barcelona host Sevilla on April 3 (8.30pm kick off).