Zola believes the current side is not good enough to lift the trophy that has so far eluded them - unless holders Barcelona suffer a massive dip in form.
"Barcelona are an exception," Zola told the Ealing Gazette. "The standard they are setting now is too high for everybody.
"It's very difficult to replicate what Barcelona are doing somewhere else because of the players they have at the moment, and the structure of their training programme, developed over many years.
"But I think Chelsea must not be discouraged by it or put off by their failure to win the Champions League so far. They have done great things in the last 10 years, and they need to keep improving."