Steyn is suffering from a side strain and pulled out after bowling just five overs during a warm-up match against Pakistan at The Oval on Monday.
"He (Steyn) is not looking good at all. We will reassess tonight and again tomorrow morning and it's still touch and go. It's not only one game and won't like to risk him," De Villiers told reporters here at the National Cricket Centre today.
"We have the experience and the energy to do our best. Against India, we will come out like a pack of wolves," he said.
Stating that the first 10-15 overs in every game will be crucial in the tournament, De Villiers said they are aware about the pros and cons of the Indian players.
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"We know a lot of about each player in their camp and we surely have our plans for them," he said.
South Africa have former Indian coach Gary Kirsten as their team boss. Quite a few players like Mahendra Singh Dhoni, Suresh Raina and Virat Kohli, who were part of the 2011 World Cup-winning squad, still remain the backbone of the Indian squad here at the Champions Trophy.
De Villiers said winning will depend on how well India or South Africa play as a team.
"It's not about individuals. We have to play as a team and we are a set one and I am very happy with the combination we have," he said.