Atletico Madrid right-back Sime Vrsaljko will not have to undergo surgery on his left knee after tests done on Monday showed no damage to his anterior cruciate ligament.
An MRI scan did show a partial tear to his posterior cruciate ligament and a medial collateral ligament sprain.
Vrsaljko suffered the injury in the opening minute of Atletico's 3-1 home win over Sevilla on Sunday when he went into a tackle and immediately went down holding his knee.
Atletico's club doctors initially feared Vrasljko had damaged his anterior cruciate ligament, which would have seen him face a long spell on the sidelines.
A statement from Atletico said: "Sime Vrasljko underwent on Monday morning an MRI which revealed a partial tear of his posterior cruciate ligament and a grade I-II sprain in his internal collateral ligament of his left knee.
"The Croatia international defender will begin treatment to recover from his left knee injury."
No time frame has been given for Vrsaljko's recovery but Marca reports that he is expected to be sidelined for a month.
The 25-year-old has started in 25 games in all competitions for Atletico.
Vrsaljko will miss Croatia's 2018 World Cup qualifier against Ukraine on Friday and is expected to miss several games for Atletico, including sitting out both legs of his team's Champions League quarterfinal tie against Leicester City, on April 13 and 19.
Atletico are fourth in La Liga, two points adrift of Sevilla, who hold the last direct Champions League qualifying spot.