Chelsea have agreed an £18m deal with Shakhtar Donetsk for Brazilian international Douglas Costa, according to reports.
The 24-year-old was regarded as one of the best young talents in Brazilian football during his time with Gremio.
Since moving to Shakhtar in 2010, his performances are said to have caught the eye of a number of top European clubs.
According to The Sun, Costa has agreed a deal in principle to join Jose Mourinho's team at the end of the season.
The attacking midfielder has played 133 times for Shakhtar, scoring 27 goals.