Toure concedes they "underestimated" the Swiss.
He said, "After the first goal, we gave up, Basle had nothing to lose today. They played a lot better here than in the first leg (City won 4-0).
"We underestimated this team and we were punished. It is necessary to prepare well, the matches to come will be more and more difficult.
"If we want to get to the final, we have to play all the matches at 100%."