Kelvin came off the bench to score a brilliant injury time winner to give Porto a dramatic 2-1 victory over Benfica in their title-deciding clash.
Porto went into the game two points behind unbeaten leaders Benfica with two games to play, so they knew anything but victory would all but hand the title to the Águias.
Benfica struck first against the run of play through Rodrigo Lima’s tap in, but were pegged back courtesy of Maxi Pereira’s own goal six minutes later.
Vitor Pereira’s side were the better side throughout but had seemed destined to hand the title to their bitter rivals.
But Kelvin's silky late volley sent the Estadio do Dragao wild as Porto celebrated an unbelievable win that puts them in pole position ahead of the last round of games.
The stakes could barely have been higher as both sides looked to end the other’s 28-game unbeaten run and take the edge into their final game.
Porto started the brighter, with Joao Moutinho seeing plenty of the ball and Jackson Martinez looking a constant threat in attack.
But Benfica drew first blood in the contest, with the Porto in disarray after Eduardo Salvio’s long throw caused panic in the Porto penalty box. Lima eventually turned the ball in at the far post after Ezequiel Garay’s shot deflected into his path.
Rather than build on their lead, though, Benfica retreated and Porto stole the initiative – and it took them only six minutes to level.
Galloping into space down the left, Silvestre Varela’s low cross deflected off the unfortunate Pereira and squeezed into his own net, with the desperate Artur Moraes unable to scramble it out at his near post.
Porto continued to dominate, but were almost undone when Oscar Cardozo bent a low free-kick around the Porto wall, but Helton Arruda pulled off what proved a vital save low to his right.
James Rodriguez seemed to have wasted Porto’s chance to win it when he went clean through but snatched at his shot, as it brushed the post on its way into the side-netting.
But Porto got the victory their performance deserved with a superb winner in the 92nd minute, with Kelvin latching onto a lofted through ball to volley a priceless winner into the bottom corner, cuing wild celebrations at the Estadio do Dragao.
Porto will now secure the title with victory over third-placed Pacos de Ferreira next Sunday.