Atletico's 1-0 win over Deportivo La Coruna came at a cost as they lost Augusto to a serious knee injury and Gimenez to a thigh strain
The 30-year-old Argentina international was stretchered off in the 14th minute after tangling with Celso Borges and was in obvious distress as he was taken down the tunnel.
A problem with his left knee already ruled the former Celta Vigo man out for a chunk of last term and it now appears his 2016-17 campaign might be over as well, although his latest injury is to his right knee.
"Tests have revealed Augusto Fernandez suffered a complete tear of the anterior cruciate ligament in his right knee," read a statement on Atletico's official website.
"He will be operated upon soon."
In addition to the luckless Augusto, Jose Gimenez looks set to be unavailable for Wednesday's Champions League meeting with Bayern Munich after becoming the second Atletico player to be forced off by injury in the first half against Deportivo.
The Uruguayan defender picked up a thigh strain and was replaced by Lucas Hernandez after 19 minutes.