Porto kept their faint Primeira Liga title hopes alive after beating Boavista 1-0 at Estádio do Dragão.
Chances were hard to come by in the first half which saw Sérgio Conceição make three changes at the break.
The Dragons were soon awarded a penalty when Ricardo Mangas brought down André Franco, Mehdi Taremi stepping up and converting the spot kick in the 59th minute.
Iván Marcano was sent off seven minutes later which increased the tension, but the Panthers were unable to find an equaliser, Robert Boženík denied by Diogo Costa in the closing stages.
The victory sees the status quo remain at the top of the Primeira Liga with four matches remaining, Porto four points behind Benfica with Braga two points further back.
Porto created the early chances with Pepê Aquino latching onto Wendell’s through ball, his cross slapped into the air by Rafael Bracali and Otávio heading wide.
Gaïus Makouta fouled Otávio on the edge of the area which saw Mehdi Taremi step up and send his free kick into the wall, Stephen Eustáquio’s follow up effort sailing over the bar.
Diogo Costa spilled a shot from Sebastián Pérez which saw the ball roll narrowly past the post, but it was Porto looking most likely to break the deadlock.
Taremi was booked for diving when he went down looking for a penalty, joining a growing list of Porto players going to ground after half-hearted challenges.
Sérgio Conceição made three changes at the break with André Franco, Galeno and Toni Martínez coming on for Stephen Eustáquio and Evanilson.
Boavista were having no problems getting the ball forward but were unable to test Costa. Their brief spell of pressure came to an end in the 57th minute when they conceded a penalty.
It came after a long throw into the box, Ricardo Mangas caught sleeping on a clearance before fouling Franco. Taremi took the ball and confidently beat Bracali from the spot.
Petit introduced Kenji Gorré for Salvador Agra in the 63rd minute and three minutes later his side were playing against 10 men.
Marcano sent off
Iván Marcano failed to control a simple back pass which allowed Mangas to steal the ball and race clear, the Spanish defender taking a red card for his team and heading for an early shower.
Makouta fired the free kick over the wall before Conceição sacrificed Martínez for Fábio Cardoso.
Mangas appeared to have won a penalty when he was brought down by Wendell but the winger was ruled offside.
Boavista boss it
Pérez made way for Robert Boženík as Boavista pressed for an equaliser and Porto dropped deeper into their own half.
Boženík and Njie went close before Petit brought on Pedro Malheiro and Joel Silva for Reggnie Cannon and Makouta.
The Panthers went close in the 87th minute when Bruno Onyemaechi’s cross was steered towards goal by Boženík, Diogo Costa coming up with a big save to preserve all three points.
By Matthew Marshall at Estádio do Dragão