Bayern Munich midfielder Thiago Alcantara could be facing "several months" out of action after picking up a muscular injury during Wednesday's 2-1 win over Anderlecht in the Champions League.
The 26-year-old had to be replaced in the 44th minute of the European match, and was pictured leaving the stadium on crutches as fears surrounding the issue grew.
Bayern boss Jupp Heynckes told reporters after the match that Thiago had picked up "a serious muscle injury", before the club's director of sport Hasan Salihamidzic claimed that the midfielder could be missing "for several months".
Thiago's position in the Spain squad for the 2018 World Cup could now be in doubt as he faces the possibility of missing a large chunk of the 2017-18 campaign.
The win over Anderlecht means that Bayern are second in Group B - three points behind Paris Saint-Germain ahead of their meeting at the Allianz Arena next month.