Chelsea manager Antonio Conte's text message informing Diego Costa that he was to be sold is thought to have been leaked.
The 28-year-old striker revealed this week that he is surplus to requirements at Stamford Bridge and will be sold on this summer, despite his 20 goals helping the Blues to a second Premier League title in three years last season.
According to Spanish publication AS, Conte told Costa of his decision with the message: "Hi Diego, I hope you are well. Thanks for the seasono [sic] we spent together. Good luck for the next year but you are not in my plan"
Costa is said to have replied with a simple "Ok".
Following the news, Costa has expressed his desire to engineer a return to Atletico Madrid, while the player's agent Jorge Mendes is believed to have opened talks with AC Milan about a potential switch.
Chelsea have already earmarked Everton frontman Romelu Lukaku as Costa's replacement.