As Real Madrid continue their post-Cristiano Ronaldo era under Santiago Solari, Barcelona will visit Atletico Madrid in LaLiga on Saturday in a battle of familiarity and ambition.
An unpredictable start to the campaign – the latest twist coming with Barca's stunning 4-3 defeat at home to Real Betis before the international break – means the title feels as up for grabs as it has since Atleti pipped the Blaugrana on the final day in 2013-14.
Diego Godin headed home for the 1-1 draw Diego Simeone's men needed to deny Lionel Messi, Sergio Busquets, Gerard Pique and the rest, making light of Diego Costa's early injury.
All those men - with the exception of the injured Godin - will be involved once more, with both teams' identities entirely ingrained. Barca might have added a few more pragmatic notes following their "take the ball, pass the ball" peak, while Simeone's men remain redoubtably "have the ball and see if we care" on these occasions.
Becoming part of the furniture in these two high castles of modern Spanish football is no easy task, with the experiences of the latest high-profile signings at Atleti and Barca acting as a cautionary tale. But two midfielders have instantly hit the mark and are set to have an influential say on how the cards fall at the Wanda Metropolitano this weekend.
Arthur: The Brazilian Xavi?
"If we were not clear about the type of player we want, Arthur would have escaped us," Barcelona sports manager Pep Segura told La Vanguardia this week, when discussing their recent arrival from Gremio.
Segura identified the 22-year-old as aligning perfectly with the Cruyffian profile of what a Barcelona player should be. His performances so far back this up.
A gentle integration into Ernesto Valverde's side appeared on the cards but Arthur has started Barca's past eight games in LaLiga and the Champions League.
The 4-2 win at Tottenham started this sequence, with the smooth style of a player intuitively protecting possession instantly recognisable. Next time out, he completed 135 of 142 passes attempted in a 1-1 draw away to Valencia.
The last player to attempt more in a LaLiga away match was Xavi against Levante in 2012. It was not the first or last time Arthur has been mentioned in the same breath as the all-time Barcelona great.
The youngster's seamless adaptation to life in Catalonia is particularly welcome as, for the first time this century, Barca line up without either Xavi or the imperious Andres Iniesta. And the man himself is a fan.
"I see myself when I see Arthur on television," Xavi told Catalunya Radio.
"He is a very quick thinker, he has a natural talent. Arthur is already a mature player and I see that he has massive untapped potential."
Rodri: Better than Busquets?
Busquets, the man who operated at the base of Barcelona's generation-defining midfield, remains as Arthur grows into his role alongside Ivan Rakitic.
As far as Busquet's heir goes, ex-Barcelona and current Spain boss Luis Enrique believes he resides at Atleti.
"It's not good to give too much praise and he is very young, but Rodri comes across as very professional and prepared mentally," he said of the languid midfielder who has excelled for club and country since joining Atletico from Villarreal.
"He can reach Busquets' level and maybe surpass it. Who knows what limits he has?"
If any Barca player were to be imitated in Simeone's team of steely efficiency, a Busquets clone seems the most obvious choice.
Rodri's ability to break-up play and tidily get Atleti on the move has already made him invaluable. His alliance with Thomas at the base of his coach's famously compact and disciplined midfield was to the fore in the recent wins over Borussia Dortmund and Athletic Bilbao, with both scoring to inspire a stunning comeback in the latter.
He is joint-fourth in the Champions League this season when it comes to possession recoveries with 36. In LaLiga, his 91.83 per cent pass completion rate is third among players to have made more than 500 passes.
Like Arthur, Rodri is 22 and viewed as vital to his country's hopes of rebuilding after an underwhelming World Cup.
"With every game he plays, he takes a step or two forward," Marca said when identifying his as a standout performer in La Roja's 1-0 friendly win over Bosnia-Herzegovina last weekend. "The Atletico midfielder continues to show that he is one of Spain's great hopes."
Establishing themselves as pivotal players at club and international level in the months immediately after career-shaping transfers speaks highly of Arthur and Rodri's quality and temperament. As does the fact that, when Atletico and Barcelona's tactical ideologies collide once more, both will probably look like they've been there for years.