Atletico Madrid defender Robin Le Normand suffered a high-grade injury to the back of his left knee during their 3-1 Champions League win over Union Saint-Gilloise, the LaLiga club said on Wednesday.

The Spain international was substituted midway through the first half of Tuesday's home game against the Belgian club after colliding with a Saint-Gilloise player and grimacing in pain.

Medical tests confirmed the injury was caused by a hyperextension of the joint.

"Further assessment carried out on Wednesday confirmed a high-grade injury to the posterior capsule and the semimembranosus muscle, but the ligaments and meniscus were not affected," Atletico said in a statement.

Spanish media reported that the 28-year-old could be out for at least a month, which would rule him out of Spain's World Cup qualifier away to Georgia on 15 November and Atletico's Champions League home game against Inter Milan on 26 November.