For the first time since he joined the club last August, Lionel Messi got to know properly the Paris Saint-Germain ultras. On Sunday, against Bordeaux at the Parc des Princes, he was booed throughout the game. It didn't matter that PSG won 3-0; Messi would have rather avoided their wrath, but it happened, and it kind of shook the football world. Here was the world's best player, arguably the best of all time, being heckled by fans who had previously flooded the streets of the French capital to greet him.

It remains unclear if the Argentine superstar knew what was coming, or if he'd been warned that things would get ugly and he'd be whistled by his own fans. But he quickly found out. He didn't looked too fazed by it, while his entourage don't sound too upset about it either. But for the wider sporting audience, the fact that PSG fans booed one of the greatest players of all time every time he touched the ball was seemingly too much to take.

First, let's remind everyone first that it's far from the first time he's experienced it. In the past, while on international duty with Argentina, his difficult relationship at times with the fans has led to some vocal frustration. But he would have certainly be surprised by the intensity of the protest and the fact that the boos lasted the whole game.

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The reaction from the Collectif Ultras Paris (CUP), which is the supporters' group containing the PSG ultras, was significant. For the CUP, their anger mirrored the humiliation of losing to Real Madrid last week and yet another early exit from the Champions League.

It's no secret that Europe's top club competition is the top goal for the club, but the latest Remontada against them clearly hurt a lot. (In the past 10 tournaments, PSG have only made it past the quarterfinal stage on two occasions, losing in the final in 2019-20 and the 2020-21 semifinal.)

These fans are passionate to a fault; equally, they were unhappy with the club before the defeat in Madrid. They feel that the direction the club is taking at the moment is one more focused on marketing than the on-pitch performances, more concerned with selling shirts or recruiting "bankable" players than winning big games or building a strong and balanced squad. They protested earlier in the season against the club's hierarchy because they feel PSG are losing their identity. They also highlighted that part in the very strong statement from Friday.

In the ultras culture, you mark your discontent with banners, boos, insults or demonstrations. Sometimes, they take it too far, though what we saw on Sunday is nothing new.

Remember the 2007-08 season, when PSG fought against relegation until the last day of the season and had a huge game in Sochaux? Earlier in that campaign, the Ultras invaded the training ground after a particular string of bad results and threatened the players and the staff. It was scary to witness as the players were prevented from leaving the training ground and their cars were damaged.

In 2017, after the ill-fated "Remontada" against Messi in Barcelona, the Ultras stormed the Bourget airport, proceeding to block the players' cars and hurl verbal abuse at them. Thiago Motta even knocked over a supporter standing in his way.

In 2019 after another Champions League collapse, this time against Manchester United, the Ultras forced their way into the Parc des Princes to attend a training session and booed and insulted the players.

PSG have a long history of tension in their relationships with the Ultras, who were banned from attending home games between 2010 and 2014 after some scenes of rare violence which led to the death of two fans in 2006 and 2010 around the Parc des Princes, one of many incidents home and away around this time as well.

Ultimately, the loss at the Bernabeu, in which they blew a commanding 2-0 lead midway through the second half, was the final straw. They wanted to protest and let their unhappiness be known, and apart from Kylian Mbappe and Keylor Navas, no PSG players were spared. Neymar was insulted, though it's nothing new for the Brazil forward.

When asked about the whole situation, defender Presnel Kimpembe said "we understand the disappointment of the fans, their anger and their screams. Neymar and Messi being booed? We are all at fault. We are a team in the good and bad moments. It is all of us. It is time to all show character."

The boos were not targeting individuals, but the entire club. It could have been Pelé, Emmanuel Macron or Michael Jordan playing -- they would have been jeered too. And it could have been worse. In the past, there had been incidents when the ultras turned up at the training ground and physically threatened the players.

Most of the supporters who protested on Sunday were in Madrid on Wednesday. Some drove all the way from Paris to the Spanish capital to see the defeat in person, and they believe they have the right to show that they feel let down.

They've been accused by some to have a short memory when it comes to Messi. Why? Because he won a Champions League back in 2015? Because he is one of the greatest? He sunk like the others at the Bernabeu, and they felt it was also his fault -- to the fans, he deserved it just like any other player. Messi had better get used to it, though, because it looks like the Ultras will continue their protest for a few more home games yet, as this tension isn't going away.

So what will happen going forward, and how can this be fixed?

In their statement on Friday, the Ultras asked for Nasser Al-Khelaifi to leave his position as president. "We know what we owe him, but it is clear that he is the right man for the job anymore. The club needs a complete reorganisation on every level and the daily presence of a president," it reads. They are protesting as much against the marketing-first direction -- and against sporting director Leonardo, who was targeted with banners in the stands -- of the club as much as the Real Madrid defeat.

For the squad itself, the players will have to work hard and redouble their efforts to rekindle the bond with fans. The best they can do this season is continue cruising to the Ligue 1 title -- PSG are 15 points clear of second-place Marseille with 10 games remaining -- given that they were also knocked out of the Coupe de France in the last-16 by Nice at the end of January. (Interestingly, one who doesn't get much of their frustration is manager Mauricio Pochettino: the fans never felt he really settled in Paris or that he really wanted to be there, especially with the constant links to Manchester United this season. But they also acknowledge that this is a hard dressing room/club to manage.)

Things should get better over time. They always do with this club, at least until the Champions League knockout stages come around again.