Diego Costa: 'I need to improve in front of goal for Spain'

Chelsea striker Diego Costa has insisted that there will be "no lack of effort" in trying to improve his goalscoring form for Spain.

The Brazilian-born player has managed to strike just once for the nation after making his debut last year.

In Tuesday night's 1-0 win over Macedonia, Costa had another frustrating run-out.

"I've got a lot to improve and I've got to start scoring goals," Costa told AS. "There will be no lack of effort on my part.

"I am always filled with ambition whenever I get called for the national team. On a personal level I am not happy because I didn't manage to score tonight although I'm happy with the victory."

At club level, during his first season at Chelsea, Costa netted 20 goals in 29 appearances.