WASHINGTON (AFP) - Around half of Americans believe the United States will play a smaller role in global affairs in coming decades, with many predicting a Chinese century, a poll said Thursday. The Washington Post-ABC News survey comes at a time of uncertainty in relations between the United States and China, which has increasingly flexed its muscle on political and trade issues. The survey found that 46 percent of Americans believed their country will play a smaller role in the 21st century than in the 20th. Thirty-two percent predicted a larger US role, with the rest saying it would stay the same. When asked only about economic clout, 53 percent expected a smaller US role this century. Forty-three percent believed the 21st century would be more of a Chinese century, while 38 percent thought it would be another American century. Many Americans were alarmed by the trend. Thirty-nine percent said it would be bad for the United States to play a smaller global role; 19 percent said it was a good thing and 40 percent said it was neither good nor bad. The poll randomly surveyed 1,004 adults by telephone. The margin of error was five percentage points. Chinas economy has been growing at a breakneck pace, fueled by a manufacturing industry that has led the Made in China label to become omnipresent in US stores. China has also bought more than 750 billion dollars in the ballooning US debt, although it cut back its holdings last year. Despite concerns in some US circles about its rise, China remains a much poorer nation than the United States. The billion-plus nations per capita income was 2,940 dollars in 2008, compared with 47,580 for the United States, according to the World Bank. The poll said the findings mirrored US concerns about Japan two decades ago. A 1991 survey by ABC News and Japans public broadcaster NHK found that 60 percent of Americans saw Japans economic strength as a threat. But Japan was just entering its lost decade of zero or negative growth.