Chelsea have been joined in the race for Metalist Kharkiv midfielder Taison by Manchester City and a host of European clubs, according to reports.
The Blues are thought to have bid around £11m to sign the Brazilian playmaker but Metalist want more money after fielding inquiries from City, Benfica and Shahktar Donetsk.
Metalist want a deal agreed by Wednesday and have given the Blues first option on making an improved bid, according to the Daily Mail.
The 24-year-old is in his third season in the Ukraine but may struggle to gain a work permit to play in the Premier League as he has yet to win an international cap for his country.