Marquee player Elano Blumer and defender Mehrajuddin Wadoo are suspended for the semifinals first leg after accumulating four yellow cards during the league phase, while midfielder Raphael Augusto injured himself to be out of the tournament.
Chennaiyin manager Marco Materazzi admitted that these players were important but suggested there were others who could still do the job for him.
"Iit would be crazy to think I can replace a player like Rafa, the best player in the whole of ISL," he added.
Chennaiyin have never won a match against Atletico de Kolkata in the past four times they have faced each other over the two editions but Materazzi remained unperturbed.
"Last year, we won two games against Kerala (Blasters) and we all saw what happened in the semifinals. Semifinal is a different game. Kolkata have an excellent team, excellent coach and the right attitude. This will be a good game," said Italian Materazzi.