Jordi Alba has emerged as a doubt for Spain's World Cup Group B opener against Netherlands on Friday.

The Barcelona left-back appeared to suffer a muscular injury in Saturday's 2-0 win over El Salvador, with La Roja's coaching staff visibly concerned on the sidelines.

As it transpired, however, head coach Vicente del Bosque revealed following the match that Alba's discomfort was due to blisters that had broken open in the second period.

Despite the relatively minor issue, it is understood that the pain caused could force the full-back to miss Spain's clash with Netherlands.

Spain are the current European and world champions.