Onyewu suffered a torn ligament and meniscus in his right knee and requires surgery that will keep him out of action for two months, according to Sporting Lisbon's official website. The injured knee is not the same one that he injured in 2009, when he tore the patellar tendon in his left knee in a World Cup qualifier against Costa Rica at RFK Stadium.
The injury will prevent Onyewu for playing for the U.S. national team in next week's friendly against Italy, where he was a good bet to start in central defense. Instead, his absence leaves Jurgen Klinsmann with a gaping hole at the position.