LA Galaxy defender Omar Gonzalez is likely to spend the next six months on the sidelines after tearing his anterior cruciate ligament.
The 23-year old centre-back was on loan to German Bundesliga club FC Nuremberg when he collided with fellow American Timmy Chandler during his very first training session.
"He wanted to show us what he is capable of and we had great hopes for him. The important thing is for Omar to get healthy again.
"In the 24 hours he spent with us we got to know him as an interesting personality and player. We wish him all the best."
Gonzalez added on Twitter:"That's really bitter for Omar," Martin Bender, Nuremberg's chief operating officer, told the Associated Press.
"Still in shock that this happened. Your support and well wishes will carry me through a strong (and hopefully quick) recovery!"