Reyna was substituted during the first half of the USA's goalless draw with Saudi Arabia earlier this week, after which it was revealed he had suffered from "muscle tightness".
His exit from that match – his country's final friendly ahead of November's trip to Qatar – set alarm bells ringing, particularly given Reyna missed much of last season with similar muscle injuries.
But Borussia Dortmund head coach Edin Terzic moved to allay fears of another long-term absence on Friday (AEST), stating: "Gio has a strain and will be out for seven to 10 days. We hope he is available to play following the Sevilla game on Wednesday."
Terzic was also able to offer a positive update on Marco Reus' fitness after the BVB captain was injured in a 1-0 win over local rival Schalke earlier this month.
"In Marco Reus' case, the injury is fortunately not as bad as first feared," Terzic added. "We hope he will be able to slowly ease his way back into team training after the weekend."
Dortmund has won five and lost two of their first seven Bundesliga games this campaign to trail surprise leaders Union Berlin by two points.