Costa facing race against time
Costa has battled a hamstring injury in recent weeks and was moved to tears after being forced off in the first 15 minutes of Atletico Madrid's 1-1 draw at Barcelona earlier this month, a game which saw Diego Simeone's side claim their first La Liga title since 1996.
The forward travelled to Serbia for specialist treatment on the injury in the build-up to Saturday's UEFA Champions League final against city rivals Real Madrid and was surprisingly declared fit to start.
History repeated, though, as Costa lasted less than 10 minutes before limping off in Lisbon, with Real ultimately going on to record a 4-1 triumph after extra time.
The 25-year-old's latest race against time now centres on the FIFA World Cup, with Costa facing a battle to be fit for the tournament.
AS claim that the Spain international has a grade one hamstring strain and needs 15 days of rest.
And Guillen is quoted by the Spanish newspaper as saying: "Diego Costa is still carrying the injury. (It is) a micro-tear in the hamstring."
Spain open their World Cup defence against the Netherlands on June 13, a repeat of the 2010 final.
They will also face Chile and Australia in Group B.