Fans of the two-time ISL winners will have to wait before seeing Keane in action, with the Irishman laid low by a persistent Achilles problem.
The news was confirmed by manager Teddy Sheringham in Kolkata during the media interaction involving five other ISL teams on Sunday. Sheringham also confirmed that 30-year-old Spanish defender Jordi Figueras will captain the side in Keane's absence.
This means ATK will definitely be without Keane in the ISL opener against Kerala Blasters in Kochi on 17th November, a rematch of the 2016 final which the Kolkata-based team won in a shootout.
Keane is also expected to be out for ATK's first home game of the season against FC Pune City on November 26th but could be fit before they travel to Jamshedpur on December 1st.
Making matters worse for the defending champions, English winger Carl Baker is also ruled out, along with Jayesh Rane, for the first two weeks of the campaign.