Sergi Roberto will miss Barcelona's Champions League tie with Napoli and the Clasico against Real Madrid after injuring one of the adductor muscles in his right thigh.
The Spain international was an unused substitute as Barca thrashed Eibar 5-0 on Saturday but Roberto, who can play at right-back or in the centre of midfield, is not part of the squad for the last-16 first-leg fixture in Naples.
Barca confirmed Roberto will miss around three to four weeks of action via a statement on their official website, which means he will also miss a vital top-of-the-table clash at Real Madrid next weekend.
One of the quirkier additions on Barca's squad list for Napoli - albeit his name was accompanied by an asterisk - was Martin Braithwaite, who cannot play in the Champions League as he is not registered.
Denmark forward Braithwaite signed in a controversial deal from Leganes this week after Barca were granted permission to make an emergency transfer outside of the window.
Barca's victory over Eibar and Madrid's defeat at Levante on Saturday means Quique Setien's men sit top of LaLiga by two points. However, Roberto's injury is the latest to have limited Setien's options for upcoming fixture.