"This is war," declared Paulo Assunçao. Well, nearly. Saturday night, 10pm. Deportivo de La Coruña versus Valencia and Depor's new signing was pulling on his armour, ready to go into battle. "My team-mates have told me what the rivalry's all about and it's going to be nearly a war," he said. "These games are always hot," agreed the Depor striker Riki. Meanwhile, one headline warned: "The enemy at the gates." By road La Coruña and Valencia are 1,033km apart, 10 hours across the country, northwest corner to east coast, 350km south of the French border, but still: when they meet, it matters. Especially to the Galicians.

It all started in 1994, when Deportivo were competing for their first ever league title. Opponents Valencia had nothing to play for – except, it later emerged, a win bonus from Barcelona, 50 million pesetas to be collected at the road-side. Deportivo, the neutral's favourite and universally liked, got a last-minute penalty. Score and they would be champions; miss and … well, it did not bare thinking about. Bebeto did not want to take it; the pressure was huge. Miroslav Djukic did not really want to either but did. He looked absolutely terrified, which was probably because he was absolutely terrified. It was an abysmal penalty. Pathetic, weak. José Luis González Vázquez saved it easily.

There should have been something apologetic about it. Instead, the keeper leapt to his feet clenching his fists, a richer man but a poorer man too. At the other end stood Deportivo's goalkeeper Francisco Liaño: "Arrieros somos y en el camino nos encontraremos", he warned. We are muleteers and our paths will cross. They did. When they met in the league the following season, fake bank notes were thrown from the Riazor stands. And then Deportivo beat Valencia in the final of the Copa del Rey – famously played over two days after a hailstorm interrupted play. "That revenge was sweet," Liaño recalled.

Meanwhile, something else was starting to happen. Deportivo and Valencia were competing to become the league's other team, genuinely big clubs. Deportivo did win the league in 2000. The previous year, Valencia had won the Copa del Rey. In a six-year spell, between them they won three league titles, two Cups, three Spanish Super Cups and had two Pichichis, plus two runners-up places, two Champions League final appearances and a semi-final, and a Uefa Cup. Deportivo took the Cup off the galácticos on their 100th birthday and in their own stadium; Valencia took the league off them. Twice. Depor and Valencia were the alternative. Real contenders.

Were. The last time they met at Riazor, Valencia sent Deportivo down to the second division, two decades later. Another episode in the rivalry perhaps, even if this time there was something apologetic about Valencia's players as they embraced their tearful opponents on the final whistle, but more proof that the days of Super Depor were long gone. This weekend, with Depor having returned to the first division, the same fate hangs over them: Deportivo started the day bottom. Meanwhile, it is coming up to five years since Valencia won anything. Sure, they have been third three years in a row, but each time they were mathematically closer to relegation than the title.

In the last seven years, they have won only one trophy between them – and the year that Valencia won the Cup, they spent much of the season fighting the drop.

Worse, this weekend they came into their Riazor reencounter in financial trouble, with Deportivo's president in the eye of the storm and Valencia's president taking tranquillisers an hour before kick-off, as he now does every week. Now, that may not sound new. For some time now, Depor's president has talked about a "war economy" and everybody knows that Valencia have two stadiums: one that they cannot afford to finish building and one that they have not been able to sell. Valencia could not even give the stadium away: Bankia had agreed to wipe out the club's €200m debt with them in return for the land but the deal feel through when Bankia itself needed bailing out by the state. But this is new; this time it is worse.

Enemy at the gates? More like through the gates, down the hall, into the drawing room and leaning back on a leather arm chair by the fire, swirling a brandy in one hand and holding a huge cigar with the other, lit with a €500 bill, while the building crumbles around them.

Just hours before Deportivo and Valencia faced each other on Saturday night, the first conference of the FASFE, the Spanish fans' association linked to Supporters' Direct, closed in Madrid. A survey carried out by the group showed that 96% of Spanish football fans are unhappy with the way that football is run. Over 50% are unhappy at the way their own club is run.

Deportivo and Valencia are not alone but their situation has been brought into sharp focus. They have become rivals on the news pages, not just the sports ones. Over the last 10 days, Valencia have been taken over by the local government, who are now looking for a buyer – someone, anyone – and Deportivo have gone into voluntary administration. The same voluntary administration their president, Augusto César Lendoiro, described as a "disgrace" when others did it.

Valencia's debt stands at €387m and that is on its way down from the €550m racked up by previous president Juan Soler, football's very own Brian Potter. Deportivo's admitted debt, meanwhile, stands at €93m, their squad and now even their bench occupied by clients of Jorge Mendes.

Valencia have been taken over by the regional government – who, having ploughed in more than €110m, also own controlling stakes in Hércules and Elche and sponsored Villarreal via Castellón airport – an airport where no planes have ever taken off or landed – after they defaulted on an interest payment. Deportivo have filed for administration, which – and here's the trick – carries no sporting penalty, after they finally admitted that they could not satisfy their debts and found their income embargoed by the state. They owe money to more than 200 institutions, companies and people. Including €107,000 to a restaurant in La Coruña even though the club owns a restaurant that was granted a Michelin star.

Not one of Deportivo's players is up to date on pay and they still owe Albert Luque €2.1m. He left seven years ago. Over at Valencia, David Villa, Juan Mata and David Silva are long gone and continued sales are inevitable, even with a budget that makes the assumption that they will reach next season's Champions League. If they do not, and they currently have Málaga, Betis and Rayo ahead of them, the decomposition will continue at even greater pace. If Deportivo are relegated again, their capacity for generating money will be hit hard: typically a relegated team can expect the money they make from TV rights to drop from €15-20m down to €2m.

Amongst the few players for whom Valencia can expect to get good money is Roberto Soldado. But he was missing this weekend through injurey. And even the date and time is not what it was: Saturday night at 10pm used to mean the weekend's biggest game, free-to-air for everyone. No more. Some rivalry.

And yet … and yet, on Saturday night, it turned out rather well. To borrow Riki's word, it was "hot". And so was he: he scored twice, the second a beauty, cutting inside from the left. Bernat, coming on in the second half for Valencia, was even better. Or maybe Manuel Pablo was just what Manuel Pablo is: a 36-year-old full-back who can no longer run very fast. Riazor was packed and noisy. There were great saves and lovely touches – one gorgeous bit of ball control from Ever Banega sticks in the mind. There was a goal in the first minute, a goal in the last minute, and five over all. Valencia took the lead, Deportivo took it back, Valencia equalised. And then in the 92nd minute, Ricardo Costa scored the winner. 3-2 to Valencia. Depor slipped to four points from safety; four points from their original rivals, Celta de Vigo. "Valencia again," lamented one headline.

When the goal went in Deportivo's players crumpled to the floor; soon one of Valencia's did. By then, Depor were down to 10 men. From the kick-off, they were down to nine. It turns out that Assunçao was right; he took his team-mates' word for it. His first game, his first red card. "Almost a war." The game resolved, defeat confirmed, the ball in Deportivo's possession, he was sent off for clothes-lining Nelson Valdez. Just for old time's sake.

Talking points

• Oh, Leo, you sneaky little cheat. Another day, another phone call. "How many this week, Ron?" "Three?" "OK, then." And so it was that Cristiano Ronaldo scored a hat-trick for Real Madrid as they defeated Getafe 4-0 at the Bernabéu, before making way for a substitute, job done. And so it was that Leo Messi scored a hat-trick for Barcelona. Only he did not make way. Instead, the cheeky scamp stayed on the pitch … and scored a fourth. This week they meet again (yes, again). It's the Copa del Rey semi-final first leg at the Bernabéu. Barcelona meet Madrid for the fourth time this season with two more games guaranteed. And, Champions League permitting, maybe two more on top of that (By the way: the second leg, in another demonstration of organisational genius, is not for a month).

• Dear Atlético Madrid fans: sorry about that. They lost 3-0 at Athletic Bilbao. It was probably the best Athletic have played all season. Fast, open, direct. And capped off with a brilliant counter-attacking goal, sweeping from one penalty area to the other.

• Dear Betis fans: sorry about that. Gah. Betis have a brilliant season, play lovely football under a fascinating coach and climb into a Champions League place. Perfect. Only, it is not. Not quite. First, they stick them on a bloody Monday, too late. But not to worry because then they head to Madrid; the team with the best away record in the league after Barcelona. This column gets all excited and goes to watch them, to talk to them, and to write all about them and how bloody good they are. So what happens? They get hammered, of course. Mind you, Rayo were superb again: it finished 3-0 and Delibasic's goal might even be the best so far this season, played out only metres away. Betis had two memorable shots: one which cracked a team-mate in the head and one which sailed over the bar … and over the wall at the end of the ground. Yes, this wall.

• Mallorca used to attack a little and win a lot. This weekend they attacked a lot – 23 shots to Málaga's five – and lost. Joaquín Caparrós (Dear Mallorca fans, etc and so on) may not hold on to his job very much longer.

Results: Celta 1-1 Real Sociedad, Levante 2-1 Valladolid, Zaragoza 0-0 Espanyol, Deportivo 2-3 Valencia, Real Madrid 4-0 Getafe, Rayo 3-0 Betis, Barcelona 5-1 Osasuna, Athletic 3-0 Atlético, Mallorca 2-3 Málaga. Tonight's game: Sevilla-Granada.

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