The eurozone's economy grew by 0.3% in the July-to-September period last year, less than previously estimated.
GDP in the 16 countries using the euro was revised down from the 0.4% reported earlier by the EU's Eurostat office.
That represents a big fall from the 1% growth registered in the second quarter of the year, from April to June.
Much of that decline was due to a big slowdown in Germany, where growth fell from 2.3% in the second quarter to 0.7% in the third quarter.
Germany's growth in the April-to-June period was hailed at the time as exceptional, as it was the country's best quarterly performance since the country's unification in 1990.
The latest figures highlight both the fragile nature of the economic recovery in Europe and Germany's key role in leading the upturn.
Third-quarter growth in the eurozone as compared with the same period in 2009 was unchanged from earlier estimates at 1.9%.
Growth over the three-month period was driven equally by household consumption, government spending and net trade, Eurostat said.