Chelsea are making a late attempt to sign Atletico Madrid and Spain midfielder Saul Niguez.
The 26-year-old was a key player as Atletico won La Liga last term, making 33 appearances.
Chelsea had thought a deal for Saul improbable but there is now confidence that a transfer can be concluded, probably on loan.
Sevilla earlier confirmed that they had rejected Chelsea's "unsatisfactory" offer for France defender Jules Kounde.
The Spanish club are standing firm over the fee required for Kounde, insisting he will not be allowed to join the Blues for less than his 80m euros release clause.