Everton are rivaling West Ham for the £25million capture of Toulouse centre-back Issa Diop.
Marco Silva is looking to reshape his defense at Goodison Park following his arrival on Merseyside.
But Hammers boss Manuel Pellegrini already has a head start in negotiations.
West Ham - who have confirmed Mario Husillos as their Director of Football - have agreed a deal in principle with Diop, the 21-year-old France Under-21 captain.
Diop has made 85 appearances for Toulouse in the last three years, and stands 6ft 4in.
But the Premier League pair will also have to fight off notable interest from Europa League finalists Marseille, Monaco and German side RB Leipzig.