With Benfica having battered Gil Vicente on Saturday, Porto picked up a crucial three points with an edgy win at Vitoria Setubal.
Porto remained within touching distance of Primeira Liga leaders Benfica courtesy of a hard-fought 2-0 win at strugglers Vitoria Setubal on Sunday.
Julen Lopetegui's Porto side failed to close the gap on champions Benfica last week, drawing 0-0 in the top-of-the-table encounter.
Benfica subsequently went six points clear with a 5-0 hammering of relegation-threatened Gil Vicente on Saturday.
But Porto quickly cut the gap back to three, having moved into the lead at Estadio do Bonfim through Yacine Brahimi's seventh league goal of the season 15 minutes in.
Jackson Martinez added a second in injury time to confirm Porto's win.
Vitoria Setubal's loss meant that Penafiel just about kept their head above water, but a 0-0 draw at home to Academica means the league's bottom club are seven points adrift of safety with just nine to play for.
Arouca are not yet out of the mire and they could only muster a 1-1 draw at Maritimo, while Idrissa Mandiang was on the scoresheet twice as Boavista defeated Moreirense 3-1.