Barcelona have revealed Jordi Alba suffered a right thigh injury in the 1-1 draw with Sevilla, though it is unclear how long the defender will be sidelined.
The left-back, who has started all three games under new coach Ronald Koeman, had to be substituted in the 75th minute of Sunday's LaLiga game at Camp Nou.
Following tests on Monday, Barca confirmed the issue for Alba, who will be "unavailable for selection until otherwise noted".
The 31-year-old will be aided by the international break in his recovery, as he has not played for Spain since a 2-1 win over Romania in September 2019.
"The tests carried out this morning have confirmed that Jordi Alba has a muscle injury in the hamstrings of his right leg," a statement from Barcelona read.
"He is unavailable for selection until otherwise noted, and the evolution of the injury will condition the player's availability."
Alba was replaced by Sergino Dest, who became the first American to play in an official game for Barcelona following his arrival from Ajax.
The teenager was unable to help his new team secure victory in the closing stages, though the result - and the absence of fans at the famous stadium - could not spoil the occasion.
"This is the stadium of my dreams, the biggest in Europe," Dest told the club's website.
"Unfortunately, because of the coronavirus, there's no public. But it's very nice."
Barca are next in action away at Getafe in LaLiga, followed quickly by a Champions League group game against Ferencvaros.