Athletic Club have been dealt a significant injury blow after winger Nico Williams was ruled out for several weeks with a groin problem.

The LaLiga side confirmed on Monday that the 23-year-old has begun specialist treatment for pubalgia, with no definitive timeline set for his return — a worrying development both for the club and for Spain with the 2026 FIFA World Cup just four months away.

“(Williams) has begun treatment with an external specialist to treat his pubalgia, with specific work that, pending his progress, will cause him to be unavailable for upcoming matches,” Athletic said in an official statement.

Spanish media reports suggest the dynamic winger could be sidelined for a number of weeks as he focuses on rehabilitation. Williams has been a key figure for Spain under Luis de la Fuente, playing an important role in their UEFA EURO 2024 triumph, and his fitness will be closely monitored at international level.

Athletic head coach Ernesto Valverde opted not to risk Williams in the weekend’s LaLiga victory over Real Oviedo, acknowledging concerns over the winger’s condition.

“Nico has problems, he’s not 100%, we can’t continue like this,” Valverde told Movistar.

Williams is now expected to miss the Copa del Rey semi-final second leg against Basque rivals Real Sociedad on March 4, a major setback for Athletic as they chase silverware.

Spain will also be hoping for a swift recovery, particularly after Lamine Yamal endured a similar groin issue earlier this season before returning to top form in recent weeks.