Diego Costa Atletico Madrid
Atletico Madrid striker Diego Costa's injury opens doors to Chelsea's Fernando TorresReuters

Spain striker Diego Costa is reportedly a big doubt for the 2014 World Cup, after the doctors warned that the Atletico Madrid star will be out of action for almost two weeks following a hamstring injury.

The 25-year-old, who was forced off the pitch just nine minutes into Atletico's clash against Real Madrid in the Champions League final, was reportedly diagnosed with a grade one tear in the femoral biceps of his right leg after undergoing tests at the Clinica Cemtro de Madrid on Monday, according to Fifa.com.

Doctor Pedro Guillen, who examined Costa, said the striker will need to rest for around 15 days, before his injury could be re-evaluated.

"Diego Costa is still carrying the injury, a micro-tear in the hamstring," Guillen told the Spanish press.

This means that Costa, who scored 27 goals from 35 appearances in La Liga this season, will not feature in Spain's pre-World Cup friendly games against Bolivia and El Salvador on 30 May and 7 June respectively.

Though Spain's first World Cup game - against Holland - starts only on 13 June, head coach Vicente del Bosque had stressed that he wants all players to be fit, before he announces the final 23-man squad on 2 June.

"[Costa] has a muscular injury and we are watching how it develops and will decide at the last moment. We have until June 2 to give the list of 23 so there is no need to rush. I hope he is there, but we also have other good options. We have agreed that Diego Costa will come to recover at the [Spanish FA's] Ciudad Deportiva and we will decide on Friday 30. I said I would like everyone to be in good condition on June 2. I am not saying there could not be an exception, but we would like everyone to be OK by then," ESPN quoted del Bosque.

Meanwhile, Costa's injury seems to have benefitted Chelsea striker Fernando Torres, who has been selected for the friendly against Bolivia.

"I had experience a year without joining up with the team, and I wanted to hear my name. I knew anything could happen. Yesterday, I was just waiting for 1 p.m. to come and to be able to hear my name. I knew I could be in or out, but now I have more chance of going to Brazil. This list is for the game against Bolivia. I am going to take advantage of this week, enjoy myself, and hopefully we can be there in the final list," Torres told ESPN.