Philadelphia Union midfielder Maurice Edu will be out for three to four months after a suffering a stress fracture in his left leg, the team announced on Wednesday.
Union coach Jim Curtin said the team originally expected him to return within the first month of the season, but that prognosis is no longer possible.
"It's been a frustrating process, I think, for everybody involved in terms of finding a diagnosis," Curtin said.
"A lot of things don't show up on MRIs or bone scans. We finally got to the bottom of it though, and the X-ray revealed there was a fracture there.
"It's a big blow to a lot of the foundation that we planned to do this year in terms of having him at the No. 6 role."
Edu, 29, joined the Union from Stoke City in January 2014.
The U.S. international played in 27 games in all competitions for the franchise in 2015, scoring one goal and providing one assist.
In his career, Edu has spent time at Rangers and Bursaspor, as well as Toronto FC.
Edu has made 46 appearances for the United States, but has not featured for his country since an April 2014 friendly against Mexico.