In and out of the Spain squad because of injuries, since choosing to represent the country rather than his native Brazil, a disappointing 2014 World Cup tournament, plus a tally of just the one goal in seven appearances. Diego Costa clearly feels he must do better.
That was the tone of his press conference with La Roja on Wednesday, as he underlined: "I've lacked scoring goals and feeling good. There's still much more I can do and hopefully, that will start now."
Continuing, the 26-year-old Chelsea striker explained: "I continue to feel as though I'm in debt. The manager and my team-mates have done so much for me and now I'm feeling happier all the time. I know everyone better and that's really good."
Although there were doubts about whether he would be called up, Costa acknowledged: "If you're not in good shape and there are others doing better, then it's only natural for the manager not to call you up. What I want to do now is work hard to continue here."
To keep his place in the Spain squad, Costa accepts: "Confidence comes from scoring goals and that's what what I must do. This team has lots of quality and I have to do much better."
Regarding his choice to represent Spain instead of Brazil, and whether he still feels it was the right decision, Costa insisted: "The only thing that bothers me with the Spanish team, is that I haven't repaid all the affection I've been given. Obviously for me it was the correct decision and I just want to demonstrate that."
"Now I feel good, I haven't got any injuries and that's something new." He assured, whilst admitting: "Perhaps there's been a little anxiety, but all that's important for me now is to play well."
After his side suffered a surprise 2-1 defeat away against Slovakia, when the two sides met in October 2014, Spain will be out to set the record straight and can top Group C this time.
Speaking of that last encounter against Slovakia, Costa noted: "They surprised us by beating us. They played a very organised game and counter-attacked, though perhaps the result wasn't fair. Now we have a much stronger mentality."
Finally and regarding the arrival of Spain colleague Pedro Rodriguez at Stamford Bridge, Costa enthused: "A player like Pedro is important in any team. He's a really good player, plus he's a great person, a nice lad, and he'll really help us a lot."
Spain take on Slovakia at the Nuevo Carlos Tartiere stadium in Oviedo on Saturday. A positive result will make them Group C leaders in the quest to secure qualification for EURO 2016, before a challenging away match in Macedonia, next Tuesday 8th September.