Everton have "an agreement in principle" to take Chelsea winger Christian Atsu on loan for the season, manager Roberto Martínez says.

Atsu has yet to appear in a match for Chelsea since his transfer from Porto.

Atsu, who joined Chelsea from Porto last summer, was immediately loaned out to Vitesse Arnhem, who finished sixth in the Eredivisie in 2013-14 with several Blues starlets among their team.