San Jose Earthquakes forward Innocent Emeghara will miss the four to six months after having knee surgery.
Innocent, 25, signed as a designated player in January but now faces a race to return to fitness before the season's end.
The Swiss international tore the meniscus in his left knee while playing against Real Salt Lake on May 1.
He had surgery at Stanford Hospital on Wednesday.
Innocent started six games in his first MLS season and scored once, a spectacular goal against the Seattle Sounders.