Diego Costa injury: Chelsea striker speaks of frustration after he is forced to withdraw from Spain squad

Striker has a long-standing hamstring injury

Diego Costa is replaced by Loic Remy on Sunday (GETTY IMAGES)

Diego Costa is cursing his luck that injuries have once again prevented him from representing Spain.

The Chelsea striker has been ruled out for Friday's Euro 2016 qualifier against Ukraine and the international friendly against Holland four days later with a hamstring injury that he suffered in a 3-2 win over Hull on Sunday.

"I was in good form, I thought everything was finally going to work out," Costa said in an interview with Spanish sports newspaper Marca. "You always arrive (to the national team) with some aches.

"But this time, I would have arrived without any pain.

"I really wanted to prove my form and my worth... but again it (injury) happened."

The Brazil-born forward, who has scored one goal in seven appearances for Spain, also missed games against Belarus and Germany in November because of a hamstring problem.

"My history with the national team is that it still hasn't really started," the 26-year-old said. "I haven't done anything yet.

"The national team is something I think of.

"I am sorry that I cannot bring what I would like to.

"Something always happens when I get close to playing for Spain.

"It bothers me from a personal standpoint but I hope this will end.

"I've gone through a lot to be in the national team and I hope good times will come."

The former Atletico Madrid player made his debut for Spain in March 2014 after turning down a call-up from Brazil.

Costa endured a disappointing World Cup in Brazil with Spain eliminated in the first round.

It was not until October last year, in his seventh appearance, that Costa finally scored his first goal for Spain.

"I am looking to succeed with Spain," he said. "The national coach and my team-mates are counting on me.

"They deserve to be paid back for the confidence that they placed in me.

"I hope I can do that on and off the pitch."

Costa's injury problems that keep him off the pitch for Spain have led to some questioning his devotion to the country.

"Sometimes it angers me that they put in doubt my commitment," he said. "I already proved that I'm enthusiastic and that I want to achieve success with the national team.

"The best way to silence the critics is to play and to do things well.

"But I haven't done that yet and hence, I have to listen and swallow (criticism).

"It is one thing is to criticise my performance, which is fair, but another to criticise my commitment."

Costa has been impressive in his debut season in England, scoring 19 goals while setting up three more in 23 league appearances to help Chelsea climb six points clear at the top of the Premier League standings.

"The Premier League is a hard league, with great teams," Costa said. "The smaller teams can beat you."

The league is physical, too.

"I always get hit but I don't complain," he said. "They tackle strong but on top of it, they don't call the foul while in Spain they did.

"Some defenders try to bring you out of games but more and more, I control myself more and try to play my game."

Costa played in last season's Champions League final for Atletico, although he came off soon after the opening kick-off because of an injury.

This season, he did not even reach the quarter-finals of Europe's elite club competition.

Chelsea were eliminated in the last 16 stages after Paris St Germain went through on away goals following a 3-3 aggregate score.

"It could be that the effort during Christmas has taken its toll as we played three games in seven days but it's no excuse," Costa said. "We had enough quality to play a different game (in London) but it was not to be.

"PSG have a great team and we have to accept it and congratulate them.

"I hope that next season we will go further than this year."

PA