Porto converted a penalty awarded following a VAR review three minutes from the end of extra time to beat AS Roma 3-1 and reach the Champions League quarter-finals after an epic finale on Wednesday.
Fernando went down as he tried to meet Maxi Pereira's low shot across the face of the goal and, after studying the pitchside monitor, the referee judged that his shirt had been tugged by Alessandro Florenzi.
Alex Telles emphatically converted the spot-kick to give Porto a 4-3 aggregate win in the round of 16 tie and heap further pressure on Roma coach Eusebio Di Francesco, who Italian media said before the match was fighting to keep his job.
Shortly afterwards, Roma also thought they had won a penalty when the referee stopped the game while the video assistant looked for a possible push by Moussa Marega on Patrik Schick but play was waved on, this time without a pitchside review.
"The VAR is there and he didn't even go and look at it," said Roma defender Kostas Manolas. "For me, it's a disgrace -- the contact was clear. I don't understand why these things always happen to us."
Italian media said Di Francesco would not speak to the media and had "isolated himself" on the team bus.
Porto defender Pepe will miss the quarter-final first leg through suspension after being booked following a clash with Edin Dzeko. The pair pressed their foreheads against each other and the Roma forward than fell over backwards.
Dzeko was also yellow-carded for the farcical incident.
Porto quickly took control and it was no surprise when they went ahead in the 26th minute.
Marega won possession, exchanged passes with Jesus Corona and slipped the ball inside for Tiquinho Soares, a Brazilian journeyman playing at his 14th professional club, to turn in from point-blank range.
Roma, however, equalised from out of the blue, helped by a schoolboy error from Eder Militao who stuck out a leg as Diego Perotti cut inside him and held his head in despair as the referee pointed to the spot.
Daniele De Rossi produced a stuttering run-up and nonchalantly sent Iker Casillas the wrong way for his first goal of the season.
Yet, after De Rossi went off injured, Porto regained control and were back in front seven minutes after the break.
Corona crossed from the left and Marega easily got away from his marker and side-footed the ball into the roof of the net from two metres to level the aggregate score at 3-3.
Roma wasted a glorious chance before the end of normal time when Pepe sent the ball straight to Perotti, but he shot high and wide from inside the penalty area.
Dzeko also missed two chances shortly before Porto's penalty, leaving the Serie A side with only themselves to blame.
"We've got to accept it, even if the way it happened is terrible to take," said De Rossi. "We didn't deserve to go out."