Sergio Conceicao’s men go into their 32nd game of the campaign with a five point lead over Benfica who have become embroiled in a fraud scandal.
The club confirmed on Wednesday that its president, Luis Filipe Vieira, is under investigation for tax evasion.
Vieira, club administrator Domingos Soares de Oliveira and two companies that manage the club and own the stadium are suspected of having defrauded the authorities of 600,000 euros between 2016 and 2017.
While the 37-time champions suffer administratively off the field, on the park they have been in woeful form.
Benfica were teetering even before the Portuguese government imposed a lockdown to stem the spread of the the coronavirus pandemic.
From being seven points clear after 17 matches of the 34-game season, they were one point behind Porto when the league was suspended in March with 10 games remaining.
After Portuguese football's restart in June, Benfica claimed only five points from their first five games.
The slump led to the resignation of coach Bruno Lage.
And though two wins and a draw have followed his departure and the arrival of Nelson Verissimo as caretaker coach, Porto have won their last three matches to extend the gap.
"It's been a spectacular collapse," said Tom Kundert, editor of the Portuguese football website Portugal.net.
"Never has a team folded in such a way," he added. "It seems harsh on Porto but they have been the least terrible of a bad bunch.
"But fair play to them though, they have got the job done. But it's been their willpower and consistency rather than the beauty of their football."
Should Porto claim the title for the 29th time in their history on Wednesday night, Benfica have a chance to salvage some pride and their season.
They play Porto in the Taca de Portugal at the Estadio Cidade de Coimbra on 1 August.
"Even if Benfica were to win the cup, I don't expect Verissimo to stay," added Kundert.
