Julián Álvarez’s attempts to leave Atlético Madrid have developed to the point where Spanish employment law has now become part of the summer transfer window.

The Argentina striker has made clear that he wants to leave the club, telling reporters during the World Cup that he believes a transfer would be best for everyone.

Atlético have made their own position equally clear.

They do not want to sell him.

The club have already rejected a €150m offer from Real Madrid, while chief executive Miguel Ángel Gil Marín has insisted that Atlético would not accept offers of €100m, €150m or even €200m.

Diego Simeone reiterated that position at the weekend, saying the club expect Álvarez to remain in Madrid.

This has left the transfer in a relatively familiar position: the player wants to leave, the club does not want him to leave and several very large numbers have failed to resolve the disagreement.

The next development has been slightly less familiar.

Sports-law experts have now pointed towards the 2005 case involving Ibai Zubiaurre, whose release clause at Real Sociedad was reduced by a Spanish court after being judged excessive and disproportionate.

Álvarez reportedly has a €500m release clause in his Atlético contract.

Former Barcelona official Toni Freixa has argued that such a figure could potentially be challenged in court because of the gap between the clause, the player’s salary and his market value.

There is currently no confirmation that Álvarez intends to take legal action.

For now, it remains another possible route through a transfer saga which has already involved Barcelona, Real Madrid, Arsenal, public declarations, rejected bids and an Atlético complaint to FIFA.

Most summer transfers are eventually completed by one club agreeing to pay another club some money.

This one may first require everyone to establish what Spanish labour law thinks.