Chelsea have reportedly "explored" the possibility of signing Everton midfielder Idrissa Gueye this summer.
The 27-year-old moved to the Toffees from relegated Aston Villa on a four-year deal last August and made 32 starts for his new side in the Premier League, contributing one goal and an assist.
According to Bleacher Report, Premier League champions Chelsea are "looking into midfield reinforcements" for their title defence and Champions League campaign and have already made enquiries for the Senegal international.
Ronald Koeman's side have rebuffed their advances, however, insisting that he "will not be available at any price" as they look to tie him down to an improved deal.
Everton are expected to lose the services of top scorer Romelu Lukaku to Chelsea this summer in an £80m deal and also face a battle to keep hold of homegrown midfielder Ross Barkley.