Liverpool may have to do without their ace striker Fernando Torres for their season opener against Arsenal.
The Iberian had sustained the injury after coming off the bench in extra-time during his country's 1-0 win over the Netherlands in the World Cup final, and has not been able to resume full training as yet.
A statement on the Spanish Football Federation's official website confirmed scans have shown the 26-year-old has suffered "a Grade 1 muscle fibre rupture in the left thigh".
According to reports from the Mirror, he is certain to miss the Reds' Europa League match against FC Rabotnicki at Anfield, and has only a slight chance of being ready to play in their Premier League opening match against Arsenal the week after.
Liverpool do not want to rush the 26-year-old back too quickly, given he already suffered an injury-plagued season previously, and manager Roy Hodgson has mentioned the Spaniard will not return until he is well and fully fit.