Chelsea have announced the signing of teenager Danilo Pantic from Partizan Belgrade.
Southampton have been drawn to play Dutch side Vitesse in the third qualifying round of the Europa League.
Eredivisie side Vitesse Arnhem have signed Chelsea forward Isaiah Brown on loan for the coming season.
Chelsea starlet Lewis Baker will spend next season on loan at Dutch Eredivisie side Vitesse Arnhem.
Vitesse beat Heerenveen 5-2 as they claimed a Europa League place with a 7-4 aggregate win in the post-season play-offs.
AZ claim a Europa League place at the expense of Feyenoord, who were consigned to the play-offs for a place in Europe.