The 30-year-old tall Serbian forward, who has played La Liga sides like CA Osasuna and SD Eibar, will be joining the side in place of Josemi who would not be able to take part in the rest of the tournament due to an injury.
"I am looking forward to Lekic who seems a good prospect for the team is also expected soon to join the side," head coach Antonio Habas said in a statement.
Having jumped to top-four after their 3-2 win in Kerala, ATK will also be bolstered by the return of their marquee player Helder Postiga who will join the side in Delhi tomorrow ahead of their match against Delhi Dynamos FC on November 14.