Luis Suarez's position could be under threat due to Antoine Griezmann's arrival at the Nou Camp

The worst-kept secret in Spanish football was confirmed on Friday when Barcelona paid Atletico Madrid 120m euros (£107.7m) to sign French World Cup-winning forward Antoine Griezmann.

But the conclusion of Barca's long pursuit of a player they also nearly bought last summer is by no means the end of the story - certainly from Atletico's point of view.

The club from the capital reacted with fury to the move, vehemently arguing they should receive an additional 80m euros because Barca - they allege - reached agreement with Griezmann back in March, when his buy-out clause was still 200m euros.

It remains to be seen whether Atletico will follow through with their threat of legal action, which could just be a bargaining tactic to extract a few more million out of Barca.

But that is only the first of many loose ends from a deal that provides more questions than answers.

Where will Griezmann fit in?

On the face of it, Griezmann should find a natural home in Barcelona's front three alongside established superstars Luis Suarez and Lionel Messi.

The new signing's versatility allows him to play anywhere across the forward line, meaning coach Ernesto Valverde can field him alongside Suarez with Messi tucked in behind, or place Griezmann on the left wing with Suarez central and Messi on the right.

Everything Barca do this season will be played out against the backdrop of dramatic Champions League collapses at Liverpool and Roma in the past two seasons, and Griezmann's flexibility, proven goalscoring skills and ability to link play should certainly aid the Catalan club's quest for European glory.

Perhaps even more important than his undoubted attacking abilities, though - as strange as this might sound for a £100m-plus forward - are Griezmann's defensive attributes.

During his five seasons with Atletico under the rigid discipline of Diego Simeone, Griezmann developed an outstanding ability to contribute in defence, regularly dropping deep to support the back line before carrying the ball forward to spark counter-attacks.

With Suarez and especially Messi offering relatively little going backwards, Barca badly a needed someone who can operate at both ends of the field to stop them from being overwhelmed in the manner of that infamous loss at Anfield. In Griezmann, they have recruited one of the best and hardest-working 'defensive' strikers in the world.

So that's that… Griezmann is a perfect fit and will slot straight in, yes? Well, it's not quite that simple…

Neymar next?

Neymar (left) is reportedly keen on a return to Barcelona

Griezmann could well be only the second costliest arrival at Barcelona this summer, with La Liga's champions also hoping to complete a sensational move to re-sign Brazilian superstar Neymar from Paris St-Germain.

Although Neymar is reportedly desperate to resume his partnership with Messi and Suarez, that deal is a long way from being finalised. PSG have no desire to sell - not cheaply, at least - and Barca can only afford Neymar by raising the funds through player sales.

A swap deal could well be the outcome, if PSG conclude that bringing in (for example) Philippe Coutinho, Ivan Rakitic and Samuel Umtiti would be a decent exchange for the unhappy Brazilian.

Coutinho, in particular, appears to have very little future at the Nou Camp. The former Liverpool star was thoroughly disappointing for the majority of last season, operating in the left wing role which will now be occupied by Griezmann and/or Neymar, and he is clearly surplus to requirements if a buyer can be found.

More controversially, the same could also be true for Ousmane Dembele. The electric but unpredictable French winger has been hindered by injuries and attitude problems throughout his two years at Barca, whose impatience with Dembele's inconsistency may lead them to use him as bait to land Neymar.

The picture is clouded by club president Josep Maria Bartomeu's recent claim that "Dembele is much better than Neymar", but the strength of conviction in those words could be tested in the coming weeks.

Suarez on the way out?

Whether Dembele stays or Neymar arrives, the purchase of Griezmann makes it plain that Suarez's status as an assured starter is under threat for the first time since his arrival at Barca in 2014.

Valverde is a conservative coach who often prefers to play with two forwards rather than three, and it's almost unthinkable he would ever choose to select a daring front four of Messi, Suarez, Griezmann and Neymar/Dembele.

The obvious answer is rotation, but the Nou Camp dressing room is built on a mutually understood hierarchy that places Messi and Suarez as the firmly established alpha males.

Suarez is likely to resist his status being threatened, and his relationship with Griezmann is already off to a rocky start: the Frenchman has regularly professed a deep love for Uruguayan culture despite having no family connections with the South American country, and Suarez made no attempt to hide his disdain for those pronouncements during last summer's World Cup.

This is all part of an intriguing subplot to Barca's transfer activities: Messi and Suarez are both 32, so there is an obvious need to freshen up the forward line. But doing so before those two stars are ready to depart centre stage is a potential powder keg, and ensuring the transition is smooth rather than acrimonious will not be easy.

Spanish trio gunning for Champions League?

With Griezmann's move following Real Madrid's capture of Eden Hazard and Atletico's deal for Portuguese wonderkid Joao Felix, three of the 10 biggest transfers of all time have been conducted by Spanish clubs this summer - and, of course, more could follow with Neymar's possible return to Barca and Real's pursuit of Manchester United midfielder Paul Pogba.

It's no coincidence that this frenzy of activity comes immediately after a rare season of failure for Spanish teams in Europe, and it's clear that Barca, Real and Atletico are determined to prevent a repeat of the Premier League's clean sweep of finalists in the Champions League and Europa League.

First, though, they will also have to do battle with each other for domestic supremacy. With the new season still a month away, La Liga is already building up to be a cracker.