In its latest World Economic Outlook， released on Thursday，... the IMF cited the U.S. economy′s weaker－than－expected performance in the first three months of the year as the major driving factor behind its decision.
The IMF warns growth could turn out even weaker though... if the issues affecting Greece and China drag on too long.
The agency says the fallout from the Greek debt crisis is hard to predict，... and could rapidly worsen if Greece leaves the eurozone.
China′s stock market rout has also played havoc with the world′s commodity markets.
The IMF also identifies some other issues that could knock the global economy off course，... including the geopolitical tensions in the Middle East and Ukraine.