Rayo Vallecano scored and The Final Countdown began. The last goal Barcelona conceded under Ronald Koeman was met by Europe booming round Vallecas. “I made a mistake,” Sergio Busquets said. “I slept and they robbed my wallet. It’s my fault.”

But on Wednesday it wasn’t just him and he wasn’t the one who paid. He had been caught out, Gerard Piqué was beaten, Jordi Alba absent and Lionel Messi in Paris. Radamel Falcao scored, someone hit play, 14,297 fans joined in, scarves twirling, and Rayo were on their way to victory. Koeman was just on his way.

Barcelona had not been beaten by Rayo in 19 years and had not been this bad since in La Liga in 34, not statistically. Defeated 1-0 by the smallest club in primera, this was their fourth away game: they have won none and scored one goal. They had lost twice in three days and five times this season, slipping to ninth.

Related: Barcelona in talks to make Xavi their new head coach after Koeman sacked

Sitting in the tiny press room under the west end of the ground, Koeman was asked whether this might mean being sacked. “Don’t know,” he said, sounding like a man who did. If only because he has known for some time.

Everyone knew it was coming, just not necessarily now. The chronicle of a death foretold, the only thing anyone laments about Koeman’s departure is that it was late. Sitting in the directors’ box Joan Laporta, the president who considered his coach another inherited problem, had seen enough.

Barcelona left Vallecas and headed north to Barajas airport to fly home. Calls were made and by the time they landed it was done. The Dutchman had been told of the decision on board. It was exactly a year since the previous president, Josep Maria Bartomeu, had finally resigned.

The official announcement was made at 00.17 in Barcelona. The statement was short and cold and made no mention of his replacement, although conversations have started with Xavi Hernández. Koeman left the club’s training ground at 01.18, with the intention of returning to say goodbye the following afternoon. Laporta had already headed off with the director of football, Mateu Alemany, and sporting vice‑president, Rafael Yuste.

There was still a lot to be done and fast – they have two games in the next five days – but the first step had been taken. It had taken a long time and yet it had been hurried too, not planned.

Laporta was elected in March and his manifesto did not identify a manager of his own, his campaign built on one promise: to keep Messi. If the Copa del Rey win and Barcelona’s ability to get back into the title race drew them momentarily closer, the way they blew it, losing to Granada and drawing at Levante, pushed them further apart again. That loss, Laporta believed, was unacceptable and in the summer the president told his coach he was going to take a fortnight trying to find a replacement. If he could not, then Koeman could continue.

He could not. Laporta sought candidates in Germany but had neither the money nor the project to promise them and so on it went. And on, and on. Koeman was backed in the market insofar as Barcelona could do anything at all given their €1.35bn (£1.14bn) debts – Memphis Depay, Eric García and especially Luuk De Jong were players he wanted – but doubts never went away.

After defeat against Benfica in the Champions League, Laporta again tried to find an alternative, even briefing that a sacking was imminent, but again he failed.

Jordi Cruyff had encouraged him to be patient – not least because the club’s international director didn’t want to find himself forced to step in – yet more significant was the cost of replacing Koeman and the absence of an alternative. Now there is one. Xavi, victorious last Friday in Qatar’s Amir Cup, is available. Laporta’s initial reluctance to turn to him, a young, untested manager who had been the key figure for his electoral rival, Víctor Font, has been overcome by circumstance too.

Koeman had always known circumstance kept him here, that this was a marriage of convenience and that Laporta had little love for him. Increasingly, he had said so publicly, the conflict out in the open. “I have ears and eyes,” he had said, acutely aware he was being constantly undermined.

In a 2min 49sec statement, he had demanded backing “in word and deed”, and set again his position once more. In short, that he didn’t have much to work with.

Realism was a recurring theme, although it sounded a lot like an excuse and the pessimism didn’t help. When he asked: “What do you want us to do, play tiki tiki tiki taka?” not only was it incendiary, the answer was obvious: well, yes.

All of that opened greater faultlines. “What I don’t like is a conformist attitude, a certain defeatism; that can’t be allowed at Barcelona,” Laporta said, but he would allow it, at least temporarily, because he did not have any alternative.

After defeat at Atlético, Koeman revealed the president had called him and backed him. They would move on together. An attempt was made to put up a united front. Club cameras showed them embracing at the training ground, all smiles. The tension was taken out of the press conferences.

“He deserves a margin of confidence,” Laporta said. “He’s very barcelonista.” Not: we like his work. Not: we know he will get this right. Not: we’re in this together. More: he scored at Wembley in 1992, remember?

Watching what was happening on the pitch, that limited confidence diminished daily, the hope they could cling on a little longer, that not too much damage would be done.

Koeman was proud of his willingness to bring kids through and his long-term legacy may well be revealed in Gavi, Nico, and Pedri. But the results were poor and, despite his protestations, so were performances. His recurring insistence Barcelona had played well did not convince; it made things worse, no sign he accepted responsibility or had identified their ills. If the problem wasn’t him – and his talk of realism is quite right, Barcelona’s decline is far deeper – nor was he the solution.

“It’s incredible that we lost this,” he said in Vallecas, but it wasn’t. Not that night or the previous nights either. Barcelona had missed a penalty, but it had been their only shot on target. And when Falcao scored, the final countdown began.

Talking points

• “I want our fans to see what they have never seen,” Falcao said. It ended up being about Koeman but this was about them too. “We have to enjoy this. It’s not every day you win against Barcelona,” said Rayo manager Andoni Iraola. He was right: they hadn’t beaten Barcelona in 19 years. Falcao hadn’t either. And yet Iraola was sort of wrong too: it is every day that they win in Vallecas. That’s five home games and five wins this season, something no newly-promoted team has done in 56 years.

Alavés 1-0 Elche, Espanyol 1-1 Athletic, Villarreal 3-3 Cádiz, Mallorca 1-1 Sevilla, Rayo 1-0 Barcelona, Betis 4-1 Valencia, Madrid 0-0 Osasuna, Celta 0-2 Real Sociedad, Granada 1-1 Getafe, Levante 2-2 Atlético

• First Betis went top, then Sevilla did, and then Real Madrid. By the following night, the close of another wild week, Real Sociedad were back there, leading a wonderfully tight table. Atlético, Madrid, and Barcelona all dropped points. After a 2-0 victory in Vigo, where the rain fell and the football was fun, La Real are now unbeaten in 13 in all competitions and have kept seven clean sheets in 11 league games, three points clear. They’re winning in all sorts of different ways too, including resisting and somehow emerging on top, exhibiting the efficiency often assumed to be the sign of champions.

When the final whistle went, Matty Ryan took off his gloves and wrang them out, his work done. An unexpected inclusion, the Australian had made some outrageous saves to see them through the storm. “Matt rescued us from a fine [mess],” said Aritz, who scored the second of la Real’s goals. Well, the referee said he did anyway, even if it was a deflection off Mikel Merino’s header. “And I’m having it,” Aritz laughed. “There’s a long way to go but this the path,” he added, and it’s starting to sound a little bit like la Real think that competing to win the league really could be possible.

• Speaking of goalkeepers, Espanyol’s 40-year-old Diego López was superb against Athletic, Iñaki Williams and R dot D dot T dot getting the goals in a 1-1 draw. “It was like there were three of him,” Marcelino García Toral said of López.

• Granada had almost all the ball (76%), most of the shots (18) and a penalty, but somehow Getafe led 1-0. Luis Suárez sent his penalty miles over and into the second tier, the ball tracing an almost impossible vertical trajectory. It seemed the points would evade them and the fans had started singing for manager Robert Moreno to leave, but then right at the very end they got a corner, magnificent man mountain Jorge Molina heading in a 97th-minute equaliser. A former Getafe player, he somehow remembered to apologise and even said he was a little “sad” about it after. Everyone else went wild.

• Alavés beat Elche, fruit of the Loum. He scored the only goal as Alavés won for the second game in a row, both against teams likely to be in the relegation battle with them (the other was Cádiz).

• “You’ll say I’m mad but I thought it was a good game,” Carlo Ancelotti said after Madrid’s 0-0 draw with Osasuna – a game in which the clearest chance fell to Osasuna’s Jon Moncayola, who hit the post. Not mad, no, but it wasn’t the best game of a fun week. Villarreal came from 3-1 down to draw 3-3, Danjuma scoring in the 96th minute. Betis were sensational as they tore into Valencia. Sevilla came from behind to equalise in Mallorca and then thought they had won it with a Lucas Ocampos goal in the 95th minute – only for the VAR to take it off them again. And Levante got two penalties, the second of them in the last minute, to draw 2-2 with Atlético. “We need to improve – urgently,” said Diego Simeone.