By Andrew Downie RIO DE JANEIRO (Reuters) - Brazil are hopeful that their Olympic soccer triumph will give the faltering senior national side a boost as they head into two key World Cup qualifiers next month. Although the Olympic tournament features under-23 teams, Brazil believe their win can signal a new beginning for the country's soccer which has been bedeviled by chaotic administration at home and poor results at senior level. Brazil are sixth in the South American World Cup qualifying group – outside the qualifying places for Russia 2018 -- and were dumped out of the Copa America by Peru in June. More...