David Villa ruled out for three weeks
"A new test will be carried out in seven days, but in the meantime the estimated recovery time is three weeks," Valencia said in a statement on their website.
Villa, La Liga's top scorer with six goals, was substituted during his side's 1-0 win over Racing Santander on Sunday and will miss Spain's World Cup qualifiers in Armenia and Bosnia on October 10 and 14.
The European champions have qualified for next year's finals.
Valencia will be without Villa for the visit of champions and league leaders Barcelona in two weeks' time.