Pique, an outspoken defender of the wealthy northeastern Spanish region's right to self-determination, had been able to cast his vote in an independence referendum deemed illegal by Madrid without obstruction on Sunday morning.
Ja he votat. Junts som imparables defensant la democràcia. pic.twitter.com/mGXf7Qj1TM— Gerard Piqué (@3gerardpique) October 1, 2017
Others were not so lucky as police fired rubber bullets and forced their way into activist-held polling stations to confiscate ballots, in many cases by violently removing activists.
Clashes left at least 92 people confirmed injured out of a total of 844 who needed medical attention, according to Catalan authorities.
"I am very proud of Catalonia and all its people," an emotional Pique told reporters as tears welled up in his eyes after a routine 3-0 win over Las Palmas in an empty Camp Nou on an otherwise extraordinary day.
"Despite how much they are incited, and despite how much they (the Spanish authorities and security forces) want them to fall into the trap, they have demonstrated peacefully and sung loud and clear."
Amid scenes of chaos and confusion outside Barça's 99,000-capacity stadium, fans were left waiting for hours before a final decision to play behind closed doors was made less than half an hour before kick-off.
"I wouldn't have played," Barcelona's most successful ever coach and current Manchester City manager Pep Guardiola told Catalan radio station Rac1.
"If in the end you play this game, you do it with the public and all the consequences."
Pique described the match, played in near-silence, as the "worst professional experience" of his career.
Barça had appealed to La Liga to postpone the game. However, when the football and security authorities refused to do so, the club feared a potential six-point penalty if they failed to fulfil the fixture.
Barcelona's president Josep Maria Bartomeu claimed the decision to play behind closed doors was one of protest at events across Catalonia, while a section of Barça fan groups had threatened a peaceful pitch invasion to interrupt the match.
'Shame' and 'Dignity'
The divided opinion over the decision was evident as two Barça board members resigned, Bartomeu confirmed after an extraordinary board meeting on Monday.
Bartomeu also announced that Barça would take part in a general strike across Catalonia on Tuesday in protest at the violence.
Barcelona-based daily Sport's front page read "Shame" above a picture of a desolate Camp Nou, and "Dignity" in defence of Pique.
The reaction of Spanish Prime Minister Mariano Rajoy's government to the escalating crisis has drawn widespread criticism both in Spain and across the world.
Pique said Rajoy was not up to the job of leading Spain.
"He travels around the world and doesn't even know how to speak English," he said.
Tennis world number one Rafael Nadal said his "heart sank" at seeing the images from Catalonia as he prepared for the China Open in Beijing. He also pointed the finger at bickering politicians.
"It is the time for both sides to use their heads. For that there has to be a willingness on both sides," said Nadal.
"It is the moment to sit down, talk and reach points of agreement so that this is not repeated."
Pique's latest declarations have once again raised the debate over his role in the Spanish national team.
Despite playing a crucial part of the Spain sides that won the 2010 World Cup and Euro 2012, Pique is routinely jeered when representing his country.
Those jeers intensified in front of just a few hundred fans at an opening training session on Monday amidst chants of "Pique leave the national team!"
He has already stated his intent to retire from international football after next year's World Cup, but insisted he could step aside sooner if Spain coach Julen Lopetegui or the federation believe his political stance to be problematic.
Pique didn't make any comment as he joined up with the Spain squad on Monday, but continued to criticise the police's response via Twitter by posting links to videos of shocking police brutality.
By Kieran Canning / AFP