American midfielder Joe Gyau is likely to be sidelined until January because of a knee injury sustained during an exhibition against Ecuador last week.

U.S. coach Jurgen Klinsmann revealed the timetable Monday, saying the Borussia Dortmund player is expected to be "out for a while."

A 22-year-old from Silver Spring, Maryland, Gyau returned to Germany and was evaluated by doctors who determined that surgery is required.

Hurt early in Friday's match against Ecuador, Gyau was diagnosed with a meniscus injury. He had said after the game he thought a four-week recovery would be a worst-case scenario.

His father, Philip, made six appearances for the U.S. national team, and his grandfather, Joseph, played for Ghana.