Vicente del Bosque is unsure of Diego Costa's fitness ahead of the World Cup for Spain.

Costa tore his hamstring in Atlético Madrid's Champions League defeat to Real Madrid.

Del Bosque must finalize his 23-man roster by June 2.

"I'm not sure Costa will make it," Del Bosque told reporters.

"We've still got time but now it's in the hands of the doctors and the medical team. We have to be cautious," he said.