The 25-year-old was forced off after just 10 minutes at the Allianz Arena, clutching his left thigh after falling while attempting a pass. Eberechi Eze replaced him as Arsenal dealt with an early setback in Germany.
"When a player has to come off with sharp pain it is never good news. We have to wait and see," Arteta told TNT Sports.
"He doesn't look good at all, but we'll have to wait and see," the Arsenal manager added, expressing concern over the extent of the injury.
Saka has endured injury problems in recent seasons. He missed seven matches last season with an Achilles issue and underwent hamstring surgery in December 2024, which kept him out of action for more than three months.
Another lengthy absence would be a significant blow to Arsenal, with the England international an important part of Arteta's attacking plans. The club are also dealing with an injury to winger Christos Tzolis, who picked up a hamstring problem while on international duty.
Arsenal must now wait for further medical assessments to establish the severity of Saka's injury and how long he could be unavailable.
Arteta's side return to Premier League action on Saturday when they host Everton at the Emirates Stadium, with Saka's fitness likely to be a major concern ahead of the match.
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