Marina Silva: From a seringueiro to Brazilian president?

On Sunday, millions of Brazilians will go to the polls to elect a president for the world's seventh largest economy.

Brazil is facing recession, as well as the challenges of widespread poverty and corruption.

The favourite to win is the current president Dilma Rousseff, who is the first woman to hold the title, and a former Marxist guerilla fighter.

But she is up against a formidable challenger, Marina Silva, a former rubber tapper in the Amazon and now the Socialist Party candidate

BBC Brazil correspondent Wyre Davies reports.