Diego Costa
Diego Costa remains Atletico Madrid's top summer targetGetty

Atletico Madrid president Enrique Cerezo has promised his team will sign a major star during the coming transfer window, amid ongoing reports saying manager Diego Simeone is after a reunion with Chelsea's Diego Costa. Marca reports Los Colchoneros have already tabled bids worth more than €50m (£41.3m, $55.6m) for the Spaniard, Gonzalo Higuain and Pierre-Emerick Aubameyang, but the Blues' number 9 is still their top priority.

Simeone set alarm bells ringing following the Champions League final defeat to Real Madrid, revealing he was considering leaving the club. Atletico also lost to their neighbours in the 2014 final and it was understood the Argentine boss wanted reassurances over the club's intentions in the summer transfer window before committing his future.

Simeone is thought to believe that his side need to match the spending of their rivals to take that next step forward and finally conquer the Champions League.

Club officials reacted quickly by signing the likes of Antoine Griezmann and Saul Niguez to new deals in order to stop them following in the foosteps of Sergio Aguero, Radamel Falcao, Diego Costa and Arda Turan by leaving the Vicente Calderon.

Atletico have also signed the highly rated Nico Gaitan and right-back Sime Vrsaljko to strengthen their squad, but Simeone is after a proven goalscorer following last season's failure of Jackson Martinez.

Edinson Cavani, Higuain, Carlos Bacca and Aubameyang have all been listed as possibilities in the role, but reports in Spain suggest that Costa is Simeone's first choice.

The 27-year-old has been linked with a move back to Atletico since last summer. During the season he admitted he would be happy to follow in the footsteps of Filipe Luis, who returned to the Vicente Calderon after just a season with Chelsea.

Atletico president Enrique Cerezo said the club would love to re-sign the Spain international, but in April called any purchase "almost impossible" – amid reports incoming Chelsea boss Antonio Conte had identified Costa as a key part of his Stamford Bridge project.

However, recent reports in the Spanish press have said Atletico are ready to make a big attempt to fulfil Simeone's wishes and sign the striker.

Asked by reporters about the potential return of Costa, Cerezo said: "We are working with the manager to bring in the best players and we will bring in the best. But stay calm. Do not get nervous."

When questioned further about the possibility of recruiting Higuain if Costa does not sign, Cerezo added: "Be quiet as there is still a lot of summer ahead. I can say that whoever comes will be an important player, but we don't rush."

Marca reveals that Atletico have launched formal offers for Costa, Higuain and Aubameyang.

Although three offers have been tabled, Atletico only wish to sign one of the trio. Marca reports the offers are between €50m and €60m, which means any accepted bid would become the club's new record transfer fee.

Chelsea paid €40m for Costa two summers ago, but Atletico would need to pay a much bigger fee to get him back. The club's economic situation has improved in the interim, however, and they still have €42m from the mid-season sale of Jackson Martinez to China to fund any big-cash moves this window.