BRASILIA (REUTERS) - The world's two largest economies, the United States and China, will again win most gold medals at the Olympics and Britain will push Russia into third place in the overall standings, Goldman Sachs predicted in a survey released on Monday.

American athletes will come away with 45 gold medals from the Rio de Janeiro Games which start on Friday, one less that they got in London four years ago, while China will win 36, two fewer than in 2012, according to the investment bank's economists.

Beyond athletic performance, economic success enhances the chances of Olympic glory, according to Goldman Sachs, because "a country is more likely to produce world-class athletes in a world-class environment".

Britain, which hosted the Games four years ago, will win 23 gold medals, six less than in 2012. But in the overall count, it will take home 59 medals, one more than Russia.

The Russian team, hit by doping bans, will collect 14 golds, 12 fewer than the recently revised total of their London haul four years ago, Goldman Sachs predicted.