Muñoz joined Osasuna from Real Madrid last summer for £4.3 million, but the deal covered only 50 per cent of his rights — meaning Madrid retain the other half of any future transfer fee plus an undisclosed buy-back clause active for three years.
His release clause is set at £34.5 million, though the unusual ownership structure means his effective cost to any buying club will be higher.
The winger has had an outstanding debut season in the Spanish top flight, registering seven goals and five assists in 36 appearances across all competitions. He completed more dribbles in La Liga than any player other than Lamine Yamal, Vinicius Júnior and Kylian Mbappé, and scored on his Spain debut in March, keeping him in contention for the World Cup squad.
Newcastle United's interest is driven primarily by Gordon's situation. Bayern Munich have been strongly linked with the England international, and The Magpies are working to identify a replacement before that saga reaches its conclusion. Muñoz, who is comfortable on either flank, fits the profile in terms of age, style and potential resale value.
Aston Villa are also in the frame. Their Champions League qualification for next season — secured by winning the Europa League — gives Unai Emery's club a significant advantage in attracting targets over rivals not in European football's top competition.
Barcelona, AS Roma and Real Madrid's own buy-back option all complicate the pursuit further. Sunderland made a bid in excess of £20 million in January but Newcastle and Villa both offer a more compelling environment for a player at this stage of his development.
The £34.5 million release clause represents a clean entry point for the right buyer. The Madrid complication means nothing is simple.