Aymeric Laporte is set for a lengthy spell on the sidelines after Athletic Bilbao confirmed he suffered a broken leg and dislocated ankle while on international duty.
Highly-rated defender Laporte, reported to be a transfer target for incoming Manchester City boss Pep Guardiola, sustained the injury to his right leg in a tackle while playing for France Under-21s against Scotland on Thursday.
The 21-year-old was carried off on a stretcher and, following scans, Athletic announced the severity of his injury on Friday.
A club statement read: "After the first scan, Aymeric Laporte has been diagnosed with a fracture-dislocation of the fibula and right ankle.
"On his return to Bilbao he will be subjected to further tests after which the extent of his injury and his period of absence will be determined."
The news represents a huge blow to Athletic, who will have to do without Laporte as they chase a top-four spot in La Liga.
Ernesto Valverde's side are also in the quarter-finals of the Europa League, where they will face domestic rivals and holders Sevilla.