MADRID -- Atletico Madrid look like they will be without the services of Spain international striker Alvaro Morata at a key moment of the season after he was forced out of Sunday's 1-0 defeat to Sevilla with a knee injury.

The forward, who is Atletico's top scorer with 19 goals this season and who has played 2,216 minutes, went down after a challenge at the end of the first half and had to be helped from the pitch and was shown crying in pain and frustration as the club's medical staff carried out a preliminary evaluation.

That ruled out a torn cruciate knee ligament, which would have ended Morata's season, and he was seen walking from the ground without crutches as Atletico began their return journey. However, the club have confirmed he has suffered a "twisted knee with trauma."

Further tests carried out on Monday confirmed that Morata has suffered a twisted internal ligament and he will be out of action for at least three weeks.

That means the striker will miss his side's Champions League last-16 tie against Inter Milan, the return leg of their Copa del Rey semi-final away to Athletic Club Bilbao, where they need to overturn a 1-0 first leg deficit, and La Liga matches against Las Palmas, Almeria, Betis, Cadiz and perhaps FC Barcelona.