U.S. international midfielder Jermaine Jones will miss six weeks to have knee surgery, his Bundesliga club Schalke told German newspaper Bild on Sunday.
Jones told the newspaper the meniscus surgery was "inevitable" because of persistent pain. Bild did not report which knee Jones injured.
The surgery will rule Jones out for the United States' final two World Cup qualifiers in October. The U.S. has already clinched a spot in Brazil.
The Americans could face Jamaica and Panama without either of their key central midfielders. In addition to Jones, Michael Bradley is recovering from an ankle injury he suffered before a September qualifier in Costa Rica.
Jones will also miss Schalke's Champions League matches against Switzerland's Basel and England's Chelsea in the coming weeks.