RIO DE JANEIRO, Feb 1 (Reuters) - Fluminense scored three times in the first half to secure a 3-0 victory over Goias on Sunday and boost their hopes of a top-six finish in Brazil's Serie A.Finishing in the top six would guarantee the Rio de Janeiro club a place in next year’s Copa Libertadores, South America’s equivalent of Europe’s Champions League.Nino put the home side ahead with a header after 17 minutes and then Martinelli added two more before the break.The result moved Fluminense up two spots into fifth place and left Goias in relegation trouble, third bottom of the table with five games remaining. (Reporting by Andrew Downie in London; Editing by Peter Rutherford )