Chelsea are angry at manager Antonio Conte for costing them a heavy sum of money over the sale of Diego Costa during the January transfer window, according to reports.

After a bitter fallout with Conte last summer, the Spain international striker was deemed surplus to requirements at Stamford Bridge by the Italian and told that he would never play for the club again.

The now 29-year-old was replaced as Chelsea’s first-choice striker by Alvaro Morata, who the Blues purchased from Real Madrid.

After Costa was told that he had no future at the Bridge, his former club Atletico Madrid – who sold him in 2014 –became interested in re-signing him. However, he had to wait till January for the transfer to go through as Atletico faced a transfer ban. The move was eventually finalised at the turn of the year for a fee of £32 million.

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At the time, Chelsea believed that they could have sold Costa for £60 million and still feel that they could have got this sum of money had Conte negotiated better. The Express claims that Chelsea are considering their legal options as they believe that Conte should admit that he mismanaged the sale and could have earned the club millions more had he negotiated the deal better; it may provide them with a loophole to terminate his contract early without penalty.

Either way, it appears highly unlikely that Conte will remain as Blues boss next season. The Chelsea board are known to not accept it if a manager fails to qualify for the Champions League. Although the Blues won the FA Cup last season, they finished fifth in the top-flight standings, failing to qualify for Europe’s elite competition for the second time in three seasons.