Real Madrid’s Welsh striker Gareth Bale has an injured soleus muscle in the back of his left calf, the club said Thursday, without saying how long he would be sidelined.

Bale was forced off after just half an hour of Madrid’s 4-0 win over Shakhtar Donetsk that opened the Spanish giants’ Champions League campaign on Tuesday.

“The player has been diagnosed with a soleus muscle injury in his left leg. His condition will be evaluated,” the club said in a short statement after medical tests on Thursday.

Last season Bale was sidelined for nearly three weeks with a calf problem.

Should the current injury be more serious, he could miss out on sealing Wales’ qualification for an international tournament for the first time since 1958 when they travel to Bosnia and Herzegovina before hosting Andorra next month.