De Jong struggles with hamstring injury, Barça not yet sure how long recovery will take

NOS Football–
Barcelona has announced that Frenkie de Jong is struggling with an injury to his right hamstring. How long he will need to recover from that is not yet clear, reports the club.
De Jong had to sign out injured on Monday for Orange’s European Championship qualifiers against France and Gibraltar, a major setback for new national coach Ronald Koeman.
The midfielder suffered his injury in El Clásico against Real Madrid, which Barça won 2-1.
Who will replace Frenkie?
On Thursday, five players of the Dutch national team signed off with stomach flu. Another setback for Koeman, for whom finding a replacement for De Jong was difficult enough,
“Frenkie has a number of qualities that not many players have,” Koeman said. “But his absence doesn’t mean we are suddenly going to change the system, that would be strange. It will be something different, though. Because the person who will now be in Frenkie’s position has a different way of playing.”