LA Galaxy defender and 2011 MLS Defender of the Year Omar Gonzalez went under the knife to repair a torn Anterior Cruciate Ligament in his left knee on Friday, the club announced.

He is expected to be out for seven to nine months, but will begin his rehabilitation later this month.

Gonzalez, 23, suffered the injury in his first day of training while on loan with German Bundesliga side FC Nürnberg last week after he and fellow American Timothy Chandler collided on a play.

The defender’s absence will surely be a blow to the Galaxy. Gonzalez was a key cog in the team’s Supporters’ Shield and MLS Cup double last season, and also played a part in LA’s run to the CONCACAF Champions League quarterfinals.

In his three years with the Galaxy, Gonzalez has accumulated 87 regular-season appearances (all starts), helped keep 41 clean sheets, and has scored five goals. He’s also twice earned MLS All-Star First XI nods.