Former European Central Bank (ECB) president Jean-Claude Trichet expressed confidence Tuesday in Greece's efforts to exit its debt crisis. Delivering a speech here, the former ECB head from 2003 to 2011 appeared optimistic about the prospects of the Greek economy and the eurozone "after the worst crisis the EU has experienced since World War II." In his opinion, the situation in the eurozone has improved dramatically, owing to the fiscal adjustment and the progress made in economic and fiscal governance. Meanwhile, he urged EU countries "not to relax, but try to keep all the country members in the eurozone." In his lecture, "Lessons of the crisis: Improving the economic and fiscal governance of the euro area," he said Greece was the most vulnerable country in the EU crisis, comparing it to U.S. investment bank Lehman Brothers, which collapsed in 2008. "We did not respect the rules, never imposed the Stability and Growth Pact," he said of the causes of the crisis. "Second, there was no observation in the evolution of the competitiveness of the EU countries." "Furthermore, we didn't have a banking union and we hadn't set up control mechanisms to prevent all this," he said, adding "the market was never united in order to be flexible, while last but not least, the structural reforms were never executed to help changes happen rapidly."