Views of the US around the world have improved sharply over the past year, a BBC World Service poll suggests.
For the first time since the annual poll began in 2005, America's influence in the world is now seen as more positive than negative.
The improved scores for the US coincided with Barack Obama becoming president, a BBC correspondent notes.
As in 2009, Germany is viewed most favourably while Iran and Pakistan are seen as the most negative influences.
Nearly 30,000 people in 28 countries were interviewed for the poll, between November 2009 and February 2010.
Fifteen of the countries have been surveyed every year since 2005, allowing long-term trends to be discerned.
In these nations - or 14 of them, not including the US itself - positive views of the US fell to a low of 28% on average in 2007, from 38% in 2005, but recovered to 35% in 2009 and 40% in this year's poll.
Meanwhile, perceptions of China in the 14 other countries have been declining - falling from 49% on average in 2005, to 34% in 2009 and 2010.
"People around the world today view the United States more positively than at any time since the second Iraq war," said Doug Miller, chairman of international polling firm GlobeScan, which carried out the poll with the Program on International Policy Attitudes (Pipa) at the University of Maryland.
"While still well below that of countries like Germany and the UK, the global standing of the US is clearly on the rise again."
China 'in neutral'
Pipa director Steven Kull noted: "After a year, it appears the 'Obama effect' is real.
"Its influence on people's views worldwide, though, is to soften the negative aspects of the United States' image, while positive aspects are not yet coming into strong focus."
He added: "While China's image is stuck in neutral, America has motored past it in the global soft-power competition."
Of the full list of 28 countries surveyed this year, the US is viewed positively in 19 (20 including the US itself), while six lean negative and two are divided.
Compared with 2009, positive views of the US jumped 21% in Germany, 18 in Russia, 14 in Portugal and 13 in Chile - though Russia and Germany continued to have a negative view of the US overall.
Meanwhile, negative opinions of the US declined by 23% in Spain, 14 in France and 10 in the UK, with the result that all three lean towards a positive view of the country.
In only two of the 28 countries, Turkey and Pakistan, do more than 50% have a negative view of the US.
Germany is the most favourably viewed nation (an average of 59% positive), followed by Japan (53%), the United Kingdom (52%), Canada (51%), and France (49%). The European Union is viewed positively by 53%.
In contrast, Iran is the least favourably viewed nation (15%), followed by Pakistan (16%), North Korea (17%), Israel (19%) and Russia (30%).
The 15 countries included in the poll every year since 2005 are: Australia, Canada, Chile, China, France, Germany, India, Indonesia, Italy, Mexico, the Philippines, Russia, Turkey, the UK and the US.