PORTO ALEGRE, Brazil, Feb 21 (Reuters) - A second-half goal from Thaciano gave Gremio a 1-0 win over Athletico Paranaense on Sunday, guaranteeing them a place in next year’s Copa Libertadores.The midfielder got the only goal of the game 13 minutes from time when he took advantage of a fortunate rebound to slam the ball into the roof of the net from close in.The result left Gremio in sixth place in the Serie A with one game to go and means that for the sixth year in a row the Porto Alegre side will play in South America’s equivalent of the Champions League.Athletico had Thiago Heleno sent off in stoppage time to complete an unhappy afternoon for the ninth-placed side.(Reporting by Andrew Downie, editing by Ed Osmond)