Ganguly scored a match-winning century in the second round match, steering his side to a six-wicket victory.
"They fought hard," he said. "But we were only at 50 percent of our game. So far the Kenya game is the only one where we fielded poorly, dropping six chances.
"Still we managed to win by six wickets. We need to be at the top of our game. Tomorrow we need to do that.
"We all know how important it is for our careers to get into the World Cup final because none of us in this team have experienced that.
"So,
Ganguly said a five-day gap since India's last match would not affect his team's sharpness on the field.
"Five days, waiting for a semi-final is quite a lot," he said. "We have had two days' break between most of our games.
"But I don't think this should matter from the point of momentum in our side."
Ganguly said he would have to monitor the weather before the day-night match. There have been showers in Durban since Tuesday night and the pitch at Kingsmead is under covers.
"We need to have an eye on the weather," he said. "Especially in the evening."