White Hart Lane's final whistle became the clásico series' starting pistol, but both participants had already been up and running for some time. This was confirmation of what has long been coming: Barcelona versus Real Madrid. Over and over and over again. Losing track is understandable, so grab a pen and take it down: Madrid and Barcelona play each other on 16 April in the league, on 20 April in the Copa del Rey final, and on 27 April and 3 May in the Champions League semi-final.

El Clásico was already the planet's most mercilessly hyped game, the two biggest clubs with the biggest names. Now there are four of these games in 18 days with every competition at stake, each game bigger than the last, a crescendo rising to the perfect climax, the ultimate victory over the bitterest of rivals. A place in the European Cup final is the prize. Spain can barely contain itself. In fact, despite some half-hearted attempts to do so, Spain has not contained itself – and the series has not even stared yet.

From the day the Champions League quarter- and semi-final draw was made and the prospect of four matches in 14 days was avoided when they were kept apart in the quarters, everyone eyed these semis. Even the disappointment of missing a Madrid-Barça final was muted. This feels even greater somehow – as if right now Wembley is meaningless, a rubber-stamping of a title that will actually be won in the next three weeks. Few expect Madrid or Barcelona to lose a final. Fewer still expected Spurs or Shakhtar to stand in the way.

Yet still players and coaches made a public show of "respect". It was too early to talk about the semi-final. Last night was a release. As Xabi Alonso left the pitch he echoed what everybody was thinking: "Now, it's a reality," he said.

This has been building for ages; the analysis and arguments, the predictions and second-guessing, the account-settling, the many questions, the intrigue and the wonder. The mutual stirring and mischief-making – some so ludicrous it is funny, some so pointed it is frightening – will crank up a notch, but it was already there. The false sensibility, the dubious moral superiority, the accusations and counter-accusations.

In Catalonia, they take every opportunity to decry Madrid, José Mourinho and Cristiano Ronaldo particularly. Even good news is twisted: when Madrid's "subs" defeated Athletic Bilbao 3-0, El Mundo Deportivo bizarrely called it "a slap in the face for Mourinho". The unashamedly pro-Real Madrid newspaper Marca criticised an advertising campaign in which Barcelona's players held up their palms – a reference to the 5-0 win in November. It was, they said "aggressive" and "provocative". Takes one to know one. When Pep Guardiola slipped up in a press conference, saying that by beating Shakhtar Barcelona would "be in the final", his tormentors at Marca flew into a fit. Arrogant! A lack of respect! He had overlooked Madrid.

No one cared that the same had been done to Shakhtar and Spurs. Barcelona versus Madrid was a certainty. Now, the prophecy has come true. The coaches cannot hide behind their next opponents: their next opponents are each other. And will be for two and a half weeks.

Nothing like this has ever happened before: the nearest was four games in 21 days in 1916, with Santiago Bernabéu getting one of the goals – and, never mind the 95-year-gap, one Catalan newspaper really did note that Barcelona had been "robbed" back then.

This is bigger. Back then, there was no European Cup at stake. A legacy, an entire season – treble winners or empty-handed losers – did not rest on it. As one Catalan newspaper put it this morning, echoing Guardiola's promise upon becoming the Barça coach: "Fasten your seatbelts". The Madrid-based AS ran on: "And now for Barça." Above the huge headline, a message of optimism "Cristiano Ronaldo: 'Barcelona are not from another world. He who laughs last laughs longest'."

The Catalan media pounced on Ronaldo's "arrogance" but he is right. These are not four games in three competitions from which both teams can emerge satisfied, spoils shared. It is a series, a saga of interconnected chapters building to a climax. By progressing from a league which has lost a little of its drama because it is Barça's to lose, to the big but undeniably secondary Copa del Rey, to the European Cup, the competition which eclipses all else, it grows with every step.

Individual games are nothing; this is bigger than that. Four battles, one war. Johan Cruyff claimed that Barcelona do not need to win all four games, they must only win two: the second and the fourth. In other words, they must win the series. Real Madrid feel exactly the same way.