His old guard beat them last Wednesday; his current troop beat them last night. Jose Mourinho must feel as though he has got the measure of Barcelona twice in the same week as he moves to within touching distance of his seventh league title in four different countries.
Real Madrid played with the same defensive resilience and organisation as Chelsea and, with far more attacking threat, they were too much for a Barcelona team looking at times uncharacteristically incoherent.
Cristiano Ronaldo emerged as their second-half hero, sweeping in the winner with a typically brutal Real Madrid counter-attack, but it will be Barcelona's poor performance that will most interest Chelsea ahead of Tuesday's second leg.
Asked if his side had played the best two defensive teams in the world in the last two games and had paid for their missed chances, Barça's coach Pep Guardiola said: "Without doubt."
When asked what he had said to the players, he added: "There is no consolation in words. They have to pick themselves up. I have not spoken to them yet. I can't because they are sad, they are down. We are not going to retain the title in the league and so we have to focus on retaining our other title in Europe."
Guardiola has done his best to keep changing the winning formula, afraid that the chasing pack would one day find a way to beat his team. But last night it looked like one change too many as a forlorn-looking Leo Messi, flanked by full-back Dani Alves and youth teamer Cristian Tello in a new-look front three, failed to inspire the Spanish champions.
Real Madrid took the lead with a scrambled goal from Sami Khedira. He looked offside as he turned the ball in after shambolic defending. Angel di Maria's corner was headed back across the face of goal by Pepe and with Victor Valdes failing to clear the ball, it dropped to Carles Puyol who looked to screen it rather than get rid of it. Khedira finished to give Real Madrid 108 goals for the season – a new record in La Liga.
Barcelona huffed and puffed but too often Messi was too far from goal when he received the ball and those who did find themselves in goal-scoring positions could not finish. Messi sent Xavi through in the first half only for the midfielder to shoot wide. How different things might have been if Xavi had played the pass and Messi applied the finish.
Goal No 109 for Real Madrid came from Ronaldo, taking him to 42 for the season in the league. It came just a minute after Barcelona's equaliser. The home side must have believed they had got themselves back into the game when the substitute Alexis Sanchez scored with almost his first touch. The goal followed a surging run from Messi which opened up the defence. But it was soon cancelled out by Ronaldo.
He has so often this season been in the shadow of Messi but he always looked a threat to a three-man defence that Guardiola will be tempted to use again on Tuesday as Barcelona go in search of a goal against Chelsea; Roberto Di Matteo will hope he decides to do exactly that.
Less happy with his lot will be Cesc Fabregas, who came on as a second-half substitute for Barcelona and headed an Alves cross just wide as the clock ran down. He has not scored since January in the league and his – and the injured David Villa's – goals have been sorely missed by a Barcelona side who hoped that Messi's scoring run was never going to end.
"If I had left others out then you might have asked, if they had played, would it have been different. Maybe with Cesc we would have won, who knows," said a disconsolate Guardiola when asked about his team selection.
Mourinho had arrived in Spain saying he wanted to become the first grand slam coach with league wins in Spain, Italy and England; now he can look forward to reaching that goal in his side's four remaining games.
It was his first win at the Nou Camp as Real Madrid's coach and only his second victory over Guardiola in 11 clasicos. The only other win handed him the Spanish Cup and last night's will mean he takes the league. The victory will also serve to make his players believe they can overturn Bayern Munich's 2-1 advantage in their Champions' League semi-final.
Should they do so, they could yet meet Barcelona again in the final of the Champions' League. But on last night's showing Barça will by no means find it easy against Chelsea.
Three games in one week – two against Mourinho's old players and one against his current side – are proving an awful run-in for Guardiola and his players.
Barcelona (3-4-3): Valdes; Alves, Mascherano, Puyol; Adriano (Pedro, 74), Xavi (Alexis Sanchez, 69), Busquets, Thiago; Tello (Fabregas, 81), Messi, Iniesta.
Real Madrid (4-2-3-1): Casillas; Arbeloa, Pepe, Sergio Ramos, Fabio Coentrao; Xabi Alonso, Khedira; Di Maria (Granero, 74), Özil (Callejon, 89), Cristiano Ronaldo; Benzema (Higuain, 90).
Referee Undiano Mallenco.
Man of the match Ronaldo (Real Madrid).
Match rating 7/10.Reuse content