Diego Costa expected for preseason training on Monday - sources

Did Chelsea misfire with Diego Costa situation? (1:57)

As reports swirl over Diego Costa's future, speculations persist on whether this could cause Chelsea to miss out on other players. (1:57)

LONDON -- Diego Costa is expected to report for preseason training at Cobham with the rest of the Chelsea squad on Monday with a deal yet to be agreed with Atletico Madrid, sources have told ESPN FC.

Atletico are the only serious suitors for Costa, who is determined to force a return to his former club after being informed by text message that Antonio Conte does not want him at Stamford Bridge next season.

But in light of Manchester United's surprise move to agree a £75 million fee with Everton for Romelu Lukaku, Chelsea are being forced to re-evaluate their options as they seek to sign a new first-choice striker ahead of the new season.

The Premier League champions have no plans to allow Costa extended leave from training until an agreement is reached for his sale, despite the fact that his relationship with Conte appears damaged beyond repair and he has reportedly begun to say goodbye to his Chelsea teammates.

Alvaro Morata is Conte's next preferred choice to replace Costa if Lukaku cannot be prevented from joining United, and there is mutual respect between the two men that stretches back to the summer of 2014, when Conte pushed for Juventus to sign him from Real Madrid.

In an interview with the Guardian in April, Morata said that Conte called him last summer to try to convince him to leave Madrid for Chelsea and added that he sees himself working with the Italian "sooner or later."

Chelsea are also reportedly ready to revive their interest in signing Swansea City striker Fernando Llorente. The two clubs failed to reach an agreement in January but Conte remains an admirer of the 32-year-old, whom he worked with in his final season at Juventus.

Llorente forged a good relationship with Morata during their time together in Turin, and signing him would free up Michy Batshuayi to leave Stamford Bridge on loan -- as well as potentially improving Tammy Abraham's chances of becoming a regular starter at Swansea.