He may have disappointed for Spain this summer, but Diego Costa has vowed to do his best to win titles at Chelsea. Mike Hewitt - FIFA/FIFA via Getty Images

Striker Diego Costa has vowed to do his utmost to deliver trophies for Chelsea.

The Brazil-born Spain striker joined the Blues from Atletico Madrid, who he helped to a first La Liga title in 18 years, breaking the duopoly of Real Madrid and Barcelona.

Jose Mourinho's Chelsea are chasing a first Premier League crown since 2010 when the new season kicks off next month.

Costa carries a heavy burden, with Mourinho bemoaning his strikers last term and Chelsea's forward recruits having a history of struggling to make a prolonged impression, apart from Didier Drogba.

"I'd say to the fans that you need to be confident that I personally will fight for this club to make sure we are in contention to win as many trophies as possible," Costa told Chelsea TV. "I'm part of a great group here of players and we will do everything we can to give the fans what they want -- and that's titles."

Costa insisted it was a straightforward choice to move to Stamford Bridge.

"It was an easy decision for me to make," he added on chelseafc.com. "We have some of the best players in the world, the best manager in the world and it's a club with great history.

"I want to improve, not only as a player but as an individual, and I believe this is the perfect place for me to do that. That's the reason I chose Chelsea and why I want to defend this shirt."

Mourinho wants Costa to perform the way he did for Atletico and the striker believes his attributes mean he is suited to the Premier League.

"One of the main things [Mourinho] said was that he doesn't want me to change," added Costa, who scored 64 goals in 134 appearances for Atletico. "It was Jose's and the club's decision to buy me and the reason they signed me was because of the way I played at Atletico.

"I don't feel I have to change much, I just have to improve fine details to become a better player, hopefully I will have a similar season to the last one."

Another Chelsea striker, Romelu Lukaku, is training with his former club Anderlecht this week in a bid to hit the ground running when he links up with Chelsea at the end of this month.

The Belgium striker has spent the past two seasons on loan and been linked with a move elsewhere, but could be given an opportunity by Mourinho this term.