Apart from Zaheer, Ishant said the Indian team would also miss opener Virender Sehwag, who is nursing an injured shoulder.
"Yes, they are our key players. Their absence will definitely be felt by the team," the lanky pacer, who had come for a promotional event, told reporters at Zirakpur, about 15 km from here.
"Absence of Zaheer will mean more load on other pacers. He is a great bowler, who was in a very fine form and he used to help me a lot in the matches. It will be difficult for us to play without him, but we will try our best to fill the gap," he said.
Asked to comment on the recent conflict between the Delhi players and the Delhi and Districts Cricket Association DDCA, Ishant evaded a reply and preferred not to comment.
He, however, maintained that he was part of the Delhi team. "I can only say that I was a part of Delhi team and I have not left them. In future also, I would play for them," he said.
On the the controversy created by the cricketers refusal to agree to the World Anti-Doping Agencys whereabouts clause, Ishant said, "We play a lot of matches at various venues and we are left leaving very little time for our personal life. So, it would be difficult to tell anybody in advance about our whereabouts."
Speaking about his own form, Ishant said he was practising hard for the upcoming tournaments.
"I am practising hard for the forthcoming tournaments. We have to constantly try and improve our performance level," he said.
Asked whether too much cricket was being played these days, Ishant said players do get fatigued sometimes but called it a part and parcel of their job.