Chelsea are set to finalise a deal worth up to 14 million ($18m) for New England Revolution goalkeeper Djordje Petrovic, sources have told ESPN.

The 23-year-old is expected to undergo a medical in the coming days ahead a move worth an initial 12.5m plus a further 1.5m in add-ons.

Chelsea expect Petrovic to compete with Robert Sánchez for the No. 1 spot after allowing Kepa Arrizabalaga to join Real Madrid on loan in addition to Edouard Mendy's departure to Al Ahli.

Petrovic has made 43 appearances for the Revolution and replaced Matt Turner, who left the MLS to join Arsenal last summer before moving to Nottingham Forest earlier this month.

Chelsea also signed American goalkeeper Gabriel Slonina from the Chicago Fire last summer but sent him back on loan before agreeing a temporary switch for this season to Belgian Pro League side K.A.S Eupen.

But Chelsea will keep Petrovic with Mauricio Pochettino's first-team squad given he only has Marco Bettinelli -- who is injured -- and 20-year-old Lucas Bergstrom to call on. Bergstrom was on the bench in Chelsea's opening two Premier League matches against Liverpool and West Ham as Sanchez's understudy.

The deal will take Chelsea's spending to around 340m - already an all-time record in a single summer by any club in history.