Five men slammed on the brakes simultaneously. Together they had been running towards Lionel Messi and together they turned and ran away from him again, as if he had flicked a switch, as if he had some kind of control over them. Which, in a way, he did. The moment that led to the second goal on a night which ended with the Camp Nou roaring their team into the quarter-finals, was an encapsulation of the power that ultimately took them there.

Messi twice sent shots through the legs of Thibaut Courtois and into the net, in the third minute and the 64th, but it was the assist for the second that effectively ended this and there was something in that image, in the way it came in the 19th minute, that may even have said as much as him scoring.

Messi saw Cesc Fàbregas lose control. Seizing upon the ball, suddenly he was away. Andreas Christensen hurtled towards him, but too late. Next came César Azpilicueta, but Messi escaped to his left. And then came the switch. As he scuttled forward, five Chelsea players ran towards him, in unison. His pass turned them in unison, collectively removed them from the game. They had not made it to him and they did not make it to Ousmane Dembélé either, who controlled and thumped into the top corner, away from Courtois. At 2-0 it was good as over.

It was Dembélé’s first goal for Barcelona and it was hugely significant. Injured attempting a backheel on his first start, he had been out for four months; when he returned, more than 100 days later, another injury added four more weeks to the wait. Dembélé is Barcelona’s second-most expensive player, and the pressure duly built, along with concerns about his ability to adapt and even his diet, but he had played with the reserves in the Super Copa de Catalunya, impressed in Málaga and now, at last, he was ready.

Selected, too. Ernesto Valverde had talked about his “unique qualities” while Sergio Busquets insisted “he looks better with every day and we believe in him”, yet his inclusion was a surprise. Dembélé had played 71 minutes against Juventus in September but not since; 19 minutes in here he had been involved in the first and scored the second. Messi embraced him.

Ousmane Dembéle takes the acclaim from Lionel Messi after the pair combined for Barcelona’s brilliantly ruthless second goal. Photograph: Kieran McManus/BPI/REX/Shutterstock

There was support then; even more significant, perhaps, was the support for André Gomes, the midfielder who had referred to a kind of “hell” and admitted that the pressure weighs upon him, and the murmuring from this stadium had affected him. When he appeared in the second half there was a huge roar and the supporters chanted his name.

Ultimately, though, it always seems to come down to that guy, and within two minutes they were chanting Messi’s name again, when he dashed into the area and hit the ball under Courtois for a second time to make it 3-0. That was the 602nd goal of his career, his 100th in this competition. None of them had arrived as fast as his first here, the strike that started it all.

Messi had missed out at the weekend because of the birth of his third son, Ciro. “He looks well to me; he’s ready,” Valverde had said, rightly. They had barely packed away the pre-match banner declaring, in English, “God save the king”, when Luis Suárez’s neat flick found him and he steered the ball between Courtois’s legs at the near post. He had been back for 127 seconds and the goal was dedicated to Ciro.

Chelsea had not yet touched the ball. They grew into it, of course, and this was not always easy for Barcelona. Yet Messi was, well, Messi. Much was made of the fact that he had not scored against Chelsea before the first leg; now he has three.

But one of the mistakes when it comes to Messi is making it all about goals; it is not; it is everything else. And if there was a glimpse of his control in the pass for Dembélé to make it 2-0, it was there in countless other touches, in the way that he turned and ran, the way he escaped opponents, who chased him, circled him but rarely caught him.

The way that even if he did not go anywhere in particular, he took them with him, returning to the start point, still facing them, still on the ball and still in control, not just of himself and the ball, but of them too. Of the game.