Ratings agency Moody's cut Greece's sovereign credit rating by a single notch to A3 from A2 yesterday and placed it on review for a further possible downgrade, spurring speculation that the government may turn to the European Union and International Monetary Fund for help as soon as today. «Although the Greek government appears to be on, or even ahead of, schedule in terms of the implementation of the actions laid out in its stability and growth program, the difficult macroeconomic and financial environment has made continued adherence to the program considerably more challenging,» said Sarah Carlson, Moody's lead analyst for Greece. The rating downgrade and soaring bond spreads may push the Greek Finance Ministry into activating the 45-billion-euro aid mechanism today, business websites reported late yesterday.