As penalties loomed and the home fans vented their frustration at referee Clement Turpin and the Porto players, it was easy to fear for Arsenal.

Mikel Arteta’s side had been the likelier winners over 210 minutes of tension, but now the tie would be decided by a test of nerve and skill from 12 yards.

Streetwise, steely and led by the irrepressible Pepe — a three-time European champion — and fiery head coach Sergio Conceicao, Porto had wanted this outcome. Arsenal had hoped to avoid it.

For all their quality and the ferocious backing of the crowd, did Arsenal have the cojones to win on penalties at the end of a gruelling two-legged tie?

Yes, they did, and a 4-2 win in the shootout following a 1-1 draw on aggregate was a landmark result for Arteta’s young side, as the club reached the Champions League quarter-finals for the first time since 2010.

Martin Odegaard, the hosts’ outstanding player, Kai Havertz, Bukayo Saka and Declan Rice all scored their penalties emphatically, and David Raya was the hero, saving twice in his biggest moments in an Arsenal shirt.

There have long been doubts over the mental fortitude of Arteta’s team and, had they gone out, Arsenal would not have been the first developing English side to find it harder to progress in the Champions League than domestically.

“It’s another big step, especially as a club,” Arteta said, after Leandro Trossard’s goal earned a 1-0 win on the night, levelling the last-16 tie. “For seven years we haven’t been in this competition and for 14 years we haven’t got this far. That tells you the difficulty of it.”

For Arteta, the result was, in many respects, a vindication: of his determination to keep playing in the face of Conceicao’s barbs and tactics; and his faith in Raya, who repaid the manager’s gamble to trust him ahead of Aaron Ramsdale with the decisive moment.

“I didn’t have to see him today [to know he could cope], I was convinced that was going to be the case,” Arteta said of the goalkeeper. “You see him those first few days here, what he had to go through and how he did it with that composure.

“You look at his body language and the decisions that he takes, he doesn’t get very affected. That’s a key quality for that position.”

The two-legged tie was, though, a slog for Arsenal. Just as in the first leg, Conceicao set up his side to contain and frustrate, and his players were both superbly-drilled and happy to resort to all the disruptive ploys in the book to exasperate Arteta, his players and the home support.

Porto refused to give Arsenal an inch and Saka, so menacing in the group stage, was particularly well shackled by left-back Wendell, who also missed in the shootout when his effort struck the post and rebounded out of play off Raya.

It was telling that the only open-play goal came from the game’s outstanding piece of quality, Odegaard displaying lovely touch before magnificently threading a pass through for Trossard in the 41st minute. The closest Arsenal came to a winner was Odegaard’s disallowed goal in the second half, chalked off for a Havertz foul on 41-year-old Pepe.

Arteta described it as a “magical night”, but it was not a performance to strike fear into the remaining clubs in the competition. The bottom line is that Arsenal will need to be better if they are to savour more occasions like this.

Already awaiting in Friday’s quarter-final draw are holders Manchester City, Real Madrid, Barcelona, Bayern Munich and Paris Saint-Germain, and they will be joined by PSV Eindhoven or Borussia Dortmund, and Atletico Madrid or Inter Milan on Wednesday night.

Each one is a heavyweight at this level, and Arsenal will be one of only two clubs, along with PSG, in the last-eight never to have won the European Cup.

Admittedly, Porto have won the competition twice previously but, for all their pedigree, they are currently third in their league and their most recent annual revenue was £141million, against £464m for Arsenal.

This was a step forward for Arsenal, but it was one, by every metric, they were widely expected to take; the level will rise again sharply. One question for Arsenal is how this run will impact their push for a first league title since 2003.

On balance, City and Liverpool — both in FA Cup action this weekend while Arsenal rest — were probably pleased with the outcome, which ensured the Gunners’ focus and resources remain stretched across two fronts.

Arteta, though, believes overcoming such a hurdle can energise his squad as they push for two huge prizes. “It’s the energy that it brings among the squad,” he said. “It can be very powerful and very useful.”