It could have been a scene from their childhood but for the 48,781 people there with them. Nico Williams had just curled in the kind of goal you’re not supposed to score with your wrong foot, falling as he sent the ball flying past Jan Oblak into the corner, and now he was standing at the north end of San Mamés, the place erupting into songs of praise. Atlético Madrid defeated, his Athletic Club teammates hugged him while all around fans who would have done likewise given half a chance began chanting his name. Then his big brother knelt down, invited him to lay his weight upon him as he always had and cleaned his boot.

When Iñaki Williams was little and Nico Williams was littler, he would often get his brother up in the morning, make his breakfast, prepare his clothes and take him to school. In the afternoon, he would be back to pick him up, bringing a sandwich. He would take Nico to games – sometimes he would referee – and to the park to play, dusting him down after. One day he won one, Nico told former Spain coach Vicente del Bosque, socking it to his sibling and prompting his brother’s mates to swap sides. Iñaki was 18, Nico 10.

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Nico was special, for sure. They both are. Within a year or so, they were at Athletic, Iñaki joining in 2012, Nico following in 2013 aged 11. Since April 2021, they have played in the first team together; now aged 29 and 21 respectively, they lead it. This Saturday’s 2-0 victory over Atlético Madrid was Nico’s 100th game for the club. It was Iñaki’s 400th, 251 of them played consecutively, a record never to be matched. It was also the game with which Athletic, the club that does tradition and identity like no other, closed their 125th anniversary. And now it was perfect.

Before the game, a statue of goalkeeper José Ángel Iribar was unveiled outside San Mamés on the spot that was once the grada general. Attended by every surviving president, the 80-year-old whose symbolism escapes adjectives – “the goalkeeper of the people” in the words of the bertsolari or street poet Jon Maia – was given a guard of honour. Jon Rahm then performed the honorary kick-off in a traditional black Iribar top, the last of 12 ambassadors over the year, including Thomas Hitzlsperger, pelotari Jokin Altuna, Honey Thaljieh, and Miguel Isasi Balanzategi, a member chosen in a draw to represent all of them. After it, a veterans’ game against Porto, the first club Athletic ever faced in Europe, ended with Aritz Aduriz finally getting the farewell he was denied by the pandemic, dinking in a Panenka.

And then in the middle, Athletic took apart Atlético, the club that began as their branch in the capital. It was, coach Ernesto Valverde said, a performance “befitting the celebrations, a great game against a great opponent”. This, Nico said, “was for Iribar”. As Alberto Barbero neatly put it in Marca, “in the morning they unveiled a statue; in the afternoon, they built a monument to football”. By half-time, Athletic had hit a post twice, sent three more efforts just wide and a penalty into the stands but not scored. Which, the law says, is when they kill you for letting them off. Instead, they just kept coming, relentless, running at Atlético from everywhere. “Those aren’t lions, they’re dragons,” said the headline in AS. And by the end, they had created 14 chances to Atlético’s three and scored two to Atlético’s nought, a scoreline Ander Herrera rightly insisted “fell short”. “They were much better than us,” Diego Simeone admitted. “In another time, the fans would have taken out the hankies but no one uses them any more,” lamented El Correo.

This may just have been the best performance from anyone so far this season. And yet it was not that much of an outlier, at least not here. Since the opening day loss to Real Madrid, Athletic have been beaten only twice – in the last minute at Barcelona and in the derby at Real Sociedad – and not at all at home, scoring two, four, four, two, three, two, three, and four at San Mamés. No one has more home goals and they already have more at San Mamés than in the whole of last season. Girona coach Michel said they were the best team his side had faced and victory took them to within two points of Atlético, just three from Barcelona.

Over their last seven matches Athletic are averaging more than 15 shots a game and have not been beaten in seven. Last season they created plenty, but scored too few: now, it’s falling into place. Gorka Guruzeta, who first made his debut back in 2019 but has been to Sabadell and Amorebieta and back, suffering two relegations in a row, has scored eight times, including the opener on Saturday. That is already more than he got last season, but it is more than goals; it is about the way it works around him. Oihan Sancet has three goals, four assists and has created 27 scoring chances this season. And then there’s them.

The best winger in Spain this season is Williams. The second best winger in Spain is also Williams. Nico has three goals and five assists. Iñaki has eight goals and three assists. Only Bryan Zaragoza has more dribbles than Nico. Only Rodrygo has more shots than Iñaki. Only Jude Bellingham, Antoine Griezmann and Borja Mayoral have more goals. No one has more assists than Nico and Iñaki is only two behind. Between them they have created 58 chances (Nico 30, Iñaki 28), tearing into teams, one of them on each side of the pitch and yet both of them on all sides, no escape from the family. Not until they departed: first Iñaki and then Nico, both to standing ovations.

Osasuna 1-0 Rayo Vallecano, Valencia 1-1 Barcelona, Sevilla 0-3 Getafe, Athletic Bilbao 2-0 Atlético, Celta Vigo 1-0 Granada, Real Madrid 4-1 Villarreal, Las Palmas 1-1 Cádiz, Real Sociedad 0-0 Real Betis, Almeria 0-0 Real Mallorca

In the first half on Saturday the two posts were theirs – one each – and in the second, it was Iñaki’s run that revived the move and led to Guruzeta’s opener. From almost the same place, Nico produced a shot as exceptional as it was unexpected – “I asked him since when he was he left footed,” Valverde said later – which secured victory and so much more. Of all the 12 anniversary ambassadors there, one must have been happiest of all – Iñaki’s and Nico’s mother, Maria – and when her eldest knelt down to wipe the boot of her youngest, it could hardly have fit better, the embodiment of belonging. An act of deference, only a little different, deeper: a warmth there, a journey, something in the photo redolent of love and a million laces tied, a thousand kits washed, of care, of pride.

Even if they did manage to get the wrong foot.

The children of Ghanaians who crossed the Sahara, Iñaki was born in Bilbao – destiny, he calls it – eight years before Nico arrived. Which, with Maria working all hours and their father Felix leaving to seek work in London, lucky if they saw him once a year, meant he was not just a brother but a dad, former Athletic coach Marcelino calling him “a true father, whose influence on how Nico is and how he behaves is absolutely decisive”. There is a reason that the lion in Nico’s tattoo is Iñaki and its cub is him. Living sacrifices and experiencing economic difficulties his brother never saw, determined he would make it for all of them, Iñaki was a strict father, the responsibility to guide also guiding him: it is not just that Williams Jr might not have made it without that paternal role, it is that Williams Sr may not have done either. Instead, they both have together – and for the best Athletic side in a decade.

When Nico went to take off his runners’ up medal after the Super Cup final in 2022, Iñaki gently admonished him, telling him to put it back on, never to forget what it had cost to get here, the dream they were living. Then he laid a comforting hand on his neck as he watched, devastated, while Madrid lifted the trophy. When Nico missed the chance that would have taken them to the Copa del Rey final last season, Iñaki headed straight to his mum’s house where Nico still lived to support him. And when Nico extended his contract a fortnight ago, allaying fears that the most exciting player Athletic have produced for a generation would walk away, Iñaki was there to plant a huge kiss on his cheek.

They would remain inseparable – at club level at least after Iñaki fulfilled a promise made to their grandfather and agreed to play for Ghana the same week Nico was called up for Spain – and the very next day Nico celebrated by scoring a brilliant goal against Rayo Vallecano, running to embrace the brother who had done the same four minutes earlier. The next time he was at San Mamés – on Saturday gone – the ground they call the cathedral and among whose congregation they had grown up, Nico did it again, providing the perfect close to Athletic’s anniversary, Iñaki there waiting for him just as he always had.