Yeah hopefully for them, martin ordegaard is a really important player for their squad and loosing him now would pose a great deal to the club performance in their campaign this season. The international break is always a time that puts some club into a tight corner because most of their star player due to how intense international football is might sustain injuries that might cost the club a great deal.
however, playing for the national team is also a pride for professional players. maybe the competition system might be changed for a sufficient rest period. but apart from all that, injuries related to players can also occur due to mistakes on the field. it can't be avoided, although, in the end, the club will receive the impact of the injured player. especially if the injury is long, it must be a blow for some coaches.
hopefully, Arteta finds a replacement option for Ordegaard in a short time and has the readiness to play. however, Arsenal needs Ordegaard's important role in the team. Arteta must be very disappointed with this.