Brazilian winger Estevao Willian will join Chelsea next summer while the club is also in talks to sign Argentine defender Aaron Anselmino.
The Blues have agreed a deal to sign Estevao, 17, from Palmeiras for an initial fee of £29m, plus performance-related add-ons.
The Brazil Under-17 international has scored four goals from 17 senior appearances in the Brazilian Serie A, Copa do Brasil and Copa Libertadores.
Meanwhile, Anselmino has been the subject of an official offer to Boca Juniors, reportedly worth between £12m and £15m.
The 19-year-old centre-back would likely move on loan to partner club Strasbourg, which is also owned by Chelsea's parent company BlueCo.