Vitolo left Sevilla to sign for Atletico Madrid this summer.
Sevilla have confirmed they will sue Atletico Madrid over the transfer of forward Vitolo, the club announced on Monday.
Vitolo signed with Atletico this summer, though he will play for Las Palmas until January because the Madrid club is still serving a transfer ban imposed by FIFA.
Atleti captured Vitolo from Sevilla in July in a deal that saw the Spain international trigger his own €37.5 million release clause.
However, Sevilla say Vitolo agreed to a contract extension with their club two days earlier and the deal could not