When Inter Milan defender Francesco Acerbi jokingly asked Manchester City star Erling Haaland for two shirts after Wednesday night’s Champions League match, he may have been pushing his luck.

Shirt swapping has long been a tradition in football, however, with many players taking great pride in the impressive collections they are able to build.

Some shirts are, naturally, in more demand than others, with one team even travelling to matches with several bags full to hand out on behalf of their star player.

But what exactly do players do with the shirts they acquire? And are all treated equally once the exchanges are carried out in front of the cameras?

Many players have shared their proud collection of football shirts on social media, with entire rooms dedicated to showcasing the most revered.

Lionel Messi, no stranger to shirt swap demands as arguably the greatest player of all time, posted a photo of his collection which showed shirts covering the walls – as well as being encased in glass both in the ceiling and floor.

Former Barcelona defender Gerard Pique said he was “sorting through my closet” when he came across a star-studded selection, which includes shirts from the likes of Messi, Andrea Pirlo and David Beckham.

Pique added he had framed the shirt he exchanged after the 2010 World Cup final, in which his Spain side beat the Netherlands, from Dutch striker Klaas-Jan Huntelaar.

But the award for the most impressive of all collections surely goes to Italy manager Luciano Spalletti.

After guiding Inter Milan back to Europe’s elite club competition in 2019, Spalletti shared his collection of “names from the Champions League”, immaculately folded to display the names of countless giants of the game.

Some players must deal with far greater demand for their shirt than others.

Messi knows this as well as anybody, but the Argentina star has developed systems for coping with that during his illustrious career.

Goalkeeper Emiliano Martinez told Prime Sport that Argentina’s national team kitman prepares 650 Messi shirts for every two games, to be distributed between players, staff, sponsors and even managers around matchdays.

It pays to have a friend on the inside. Martinez is frequently inundated with requests for Messi shirts and, at the 2022 World Cup, he softened the blow of Poland’s defeat by Argentina for Aston Villa team-mate Matty Cash by gifting him with one.

But it’s not just all about the biggest names. Wayne Rooney admitted that his arrogance while playing meant he would never ask for a shirt from an opponent; however, he would always respect any player who asked for his.

And so, while he does not have a shirt from the likes of Zinedine Zidane, the former England and Manchester United star does have an Andorra shirt from Ildefons Lima – who was delighted to discover Rooney had kept it.

“I always respected any player who came up and asked for my shirt,” Rooney told BBC 5 Live earlier this year.

“I’ve seen players where they just throw it into the kit and aren’t interested, whereas I’d always show respect and take it home and keep the shirt.”

Former Premier League defender Nedum Onuoha took a different approach, placing more value on the shirts of team-mates, specifically those whom he played alongside in Manchester City’s academy and at youth level for England.

“I didn’t end up swapping that many shirts, but the shirts I did swap were with people who I came up through the academy with or played alongside for England Under-21s,” Onuoha told BBC Sport.

“Most of us came from similar places. Our journeys went in different directions but I saw what it took for them to get here. There’s a lot of meaning behind them.”

On his favourite shirts, he added: “I have some of my early City ones in frames and an England Under-21s shirt from my debut when I scored as well, somehow.

“One of my favourites is from a pre-season friendly against Barcelona. I never asked for shirts because I was too shy. They were probably one of my favourite teams.

“After the game there were lots of shirt swaps and one which happened to be available was Seydou Keita’s, one of my favourite players. I couldn’t have taken it any quicker and it still means a lot to me.”

The tradition of shirt swapping is said to have started when France, after defeating England, asked to exchange with their opponents to remember the 1931 win.

One of the most famous exchanges in history came in 1970, when Brazil icon Pele and England great Bobby Moore exchanged shirts following the World Cup group match between the two nations in Mexico.

Today’s shirt collections are a source of admiration and pride for many. With retro football shirts seemingly as popular as ever, it is a tradition unlikely to die out.

But one certain no-no to surface in more recent years is the half-time shirt swap.

Mario Balotelli was rebuked by Liverpool after swapping shirts with Real Madrid’s Pepe as his side trailed 3-0 at half-time in 2014, while in 2016 Eden Hazard was jeered by Chelsea fans for a similar exchange with Paris St-Germain winger Angel di Maria.

During last year’s Champions League campaign, Haaland was asked to swap shirts at half-time by Young Boys captain Mohamed Ali Camara, whose manager said after the 3-0 loss he would “have a word with him”.

Former Manchester United boss Alex Ferguson was also less than impressed when striker Ruud van Nistelrooy returned to the dressing room with a Manchester City shirt following a 3-1 loss to their bitter rivals.

It’s not all about building collections either.

Former England midfielder Steve Hodge made £7.14m from selling Diego Maradona’s ‘Hand of God’ shirt from the 1986 World Cup quarter-final at auction in 2022.

Meanwhile, a shirt said to be Phil Foden’s from England’s Euro 2020 quarter-final against Ukraine, given to goalkeeper Georgiy Bushchan, was recently listed on eBay for £2,999.

Former Premier League striker Chris Sutton said of his collection: “My kids have got some of them, but I’ve got my favourite shirt framed, which is Henrik Larsson’s shirt when he came back to Celtic with Barcelona.

“I never used to like swapping shirts if we had lost. I was never one of those players who would ask someone for a shirt at half-time, either.

“So I wasn’t that bothered about doing it, although I have changed my view now I’ve stopped playing.

“I wished I’d been more forthcoming about doing it after seeing how Steve Hodge got on with Diego Maradona’s shirt but, being serious, they are nice things to have when you look back on your career.”