Earthquakes center back Eddie Robinson will undergo season-ending surgery to repair his ruptured tendon in his hamstring.
Robinson was injured in the Quakes' game at Colorado on Saturday. In the same game, Colorado captain John Spencer pulled his left hamstring. He is expected to be out three weeks.
San Jose is already depleted in the back. Chris Roner (complications from ankle surgery) is out for the season, and Todd Dunivant (left quadriceps strain) is still sidelined.
Meanwhile, San Jose's promising teenager, Antonio Alvarez, sprained an ankle in practice Tuesday while trying to avoid a tackle by fellow midfielder Brian Mullan.
Two players -- Cory Gibbs (Dallas) and Dal Califf (Los Angeles) -- were scratches for the USA-Mexico game before of weekend injuries.
Elsewhere, veteran U.S. national team striker Joe-Max Moore sprained his right knee Sunday in the New England game against the MetroStars and is out for at least six weeks.