First came the stillness of mourning, then a defiant roar of “We are not afraid” as tens of thousands of Barcelona football fans started the new La Liga season by paying their respects to the victims of Thursday’s terrorist attacks.

With emotions still raw in the Catalan capital following the car attacks that killed 13 people on Las Ramblas boulevard and another person in the town of Cambrils, the phrase “only a game” had rarely felt more appropriate ahead of the kick-off against Real Betis, which Barcelona won 2-0.

But as Lionel Messi and his teammates took the field in black armbands, supporters and city officials alike highlighted the role the team could play in helping the city ease back into familiar routines at the end of three days of mourning.

“Returning to normality is a way of defeating those who want to disrupt normal life. Football is part of that,” the Catalonian president, Carles Puigdemont, told the Guardian.

At one end of the stadium, a block of several hundred supporters all wore black – rather than the normal colours of the Catalan flag – as a mark of respect. “It’s just for today. We wanted to remember the victims. It is too sad,” said one of them, who gave only his nickname, Chav.

Lionel Messi of FC Barcelona. Photograph: Bagu Blanco/Rex/Shutterstock

It is now a familiar scene, after similar memorials at football stadiums after attacks in Paris, Manchester and Dortmund.

But Barcelona FC considers itself “Més que un club” (more than a club) – a motto – that reflects the strong political and social influence of this sporting institution, which was a focus of Catalan independence aspirations during the military dictatorship of General Francisco Franco.

More recently, it may have become better known for trophy triumphs, millionaire superstars and sponsorship deals with Qatar airlines and Rakuten, but it donates money to Unicef and it is the name of that children’s charity that adorns the team’s kit.

“Barcelona is a special club. I think at this moment, it can help the city. If people are afraid, they can come here. They can see how we overcome fear and move on,” said a steward, Helena Helgarejo.

Special shirts were produced for the opening game against Real Betis that bore the hashtag #TotsSomBarcelona (We are all Barcelona) on the chest. On the back, the players’ individual names have been replaced by the collective “Barcelona”.

Flags at the stadium have been flying at half-mast since the attack happened. As has been the case for all major sporting games in Spain this weekend, players of both teams wore black armbands and stood on the centre circle for a minute’s silence – unusually accompanied by violin music over the tannoy.

Although police stepped up security around the 99,000-capacity venue, Barcelona’s manager, Ernesto Valverde, stressed that the overriding sentiment should be “We are not afraid” – a phrase that has been echoed repeatedly since the attacks.

“We have to stand up and the best way is by moving forward,” the coach of the team said after a memorial service on Friday. “We all know the way the world is. We are all potentially victims at any given moment, whether it be going to the metro station or going to a football ground. But it’s something you can’t control and we can’t hide.”

He noted how recent events have put the problems of the club (which was forced to sell one of its best players, Neymar, in the close season) in perspective.

Many of those who came were foreigners who wanted to experience the Camp Nou – the home of a club with a global brand. Football, like tourism, is a global industry, and also a potential “soft target” for terrorists.

Danish tourist Maja Ejsing said she had decided to come on the spur of the moment, despite a degree of unease. She and her boyfriend were staying in a hotel beside Las Ramblas on Thursday and saw people shouting. It was a shock that being in the crowd had helped to overcome.

“It has been very touching in Las Ramblas to see people come out and stand up for their beliefs. My boyfriend asked me if we really wanted to go. There is some concern in the back of my mind, but life must go on.”