Porto won Portugal's Primeira Liga in their first season under coach Sergio Conceicao on Saturday after a goalless draw between Sporting and Benfica ended both teams' chances of catching them.
The stalemate left Sporting and Benfica four points behind Porto with one match each to play, ending Benfica's run of four successive titles.
Benfica midfielder Rafa Silva twice hit the woodwork in the first half as the Eagles tried desperately to keep alive the title race for another week.
There was a boisterous atmosphere at the Alvalade stadium and play was interrupted after three minutes when firecrackers rained down on Sporting goalkeeper Rui Patricio's penalty area.
There was another delay at the start of the second half due to a problem with the cables supporting an aerial television camera.
Porto, who host Feirense on Sunday, have 82 points from 32 games, with Benfica and Sporting on 78 from 33. It was their 28th league title and their first since 2013.