As the wallets of the continent's biggest teams continue to grow, so too do their online presences. Social media is also increasingly driving revenue for clubs as brands target players with large followings for sponsorships.
Earlier this year, financial services firm Deloitte released its annual Football Money League, charting the massive revenues of Europe's biggest football clubs.
As the wallets of the continent's biggest teams continue to grow, so too do their online presences.
Social media has become a crucial part of the way the largest clubs connect with their fans around the world, with some even hosting foreign language Twitter accounts.
Social media is also increasingly driving revenue for clubs as brands target players with large followings for sponsorships.
There is still some disparity, though, between the clubs with the most money and the clubs with the most fans (on social media, anyway).
Scroll down to see who are the most popular teams from Deloitte's rich list, ranked in ascending order of combined followers on Facebook, Instagram and their biggest Twitter page — rounded to the nearest hundred thousand.
20. Schalke 04 — 4.1 million followers
Followers (millions):
Facebook: 2.9
Instagram: 0.5
Twitter: 0.7
The "04" stands for when the Club was founded… in 1904. With that much history, you can bet the team has built up a huge fanbase, and much of that has migrated online.
Though the club is one of Germany's wealthiest and most stable, its place in the Money League is under threat because of its absence from UEFA competitions this season.
19. West Ham United — 4.3 million followers
Followers (millions):
Facebook: 2.3
Instagram: 0.6
Twitter: 1.4
A surprisingly low Facebook following puts East London's West Ham near the bottom of the list.
Their most-followed player is the Mexican forward Javier "Chicharito" Hernandez, who has 5.2 million followers on Instagram.
18. Southampton FC — 4.5 million followers
Followers (millions):
Facebook: 3.1
Instagram: 0.3
Twitter: 1
This is Southampton's first ever appearance in the Money League and it is largely because of broadcasting revenue, which accounts for £143 million of the club's total revenue.
The club signed Danny Ings during the transfer window who has almost 700,000 followers on Instagram.
17. Everton FC — 5.4 million followers
Followers (millions):
Facebook: 3.1.
Instagram: 0.7
Twitter: 1.6
The Toffees' social accounts will have benefited from a season with Wayne Rooney, who has 12.5 million followers on Instagram alone.
Although Rooney has now jetted off to the MLS to play for DC United, Everton made three major signings in a remarkable end to the transfer window, including the former FC Barcelona midfielder André Gomes, who has over 2 million Instagram followers.
16. Napoli — 6.5 million followers
Followers (millions):
Facebook: 4.1
Instagram: 1
Twitter: 1.4
Napoli lost the Serie A title to Juventus by just four points last year — a performance that saw revenues increase to earn the southern Italian side a place in the Money League.
Belgian forward Dries Mertens has 1.2 million followers on Instagram.
15. Leicester City — 9.7 million followers
Followers (millions):
Facebook: 6.5
Instagram: 2
Twitter: 1.2
Leicester City gatecrashed the Money League last season when it ranked 20th. The club has since climbed to 14th in the financial table thanks to its participation in the Champions League and gained one place in the social media ranking.
Deloitte says the key to further inclusion on its lists will be regular top 10 finishes in the Premier League.
14. Inter Milan — 13.8 million followers
Followers (millions):
Facebook: 10.2
Instagram: 2
Twitter: 1.6
Inter Milan has gained over 5 million followers since February last year — an increase that exceeds 60%.
This aligns with the club's profits, which are up 137% on the year before.
13. Tottenham Hostpur — 15.5 million followers
Followers (millions):
Facebook: 10.1
Instagram: 2.4
Twitter: 3
Spurs are up one place since February last year. They placed second in the Premier League last season and its run in the Champions League this season has caused a financial windfall and a boost to their online presence.
Mercurial midfielder Dele Alli has done social media campaigns with the likes of BooHoo Man.
12. Atlético Madrid — 22.7 million followers
Followers (millions):
Facebook: 13. 8
Instagram: 4.9
Twitter: 4
Despite toppling their Madrid rivals in the UEFA Super Cup recently, Atletico is way behind Real both in terms of cash flow and social following.
Their striker Antoine Griezmann has almost 21 million Instagram followers.
11. Borussia Dortmund — 23.9 million followers
Followers (millions):
Facebook: 15.2
Instagram: 5.5
Twitter: 3.2
Dortmund had the highest average match attendance of any Bundesliga club last season, according to worldfootball.net. Unsurprisingly, that resulted in a lot of social media traffic.
The club's biggest star Marco Reus has 6.9 million followers on Instagram.
10. Manchester City — 49.3 million followers
Followers (millions):
Facebook: 35.2
Instagram: 7.8
Twitter: 6.3
Manchester City lands a total five places below their place on the Deloitte Money League as its budget outweighs its fan base.
However, City is still a developing club and its position as an economic powerhouse should see it grow comfortably on social media as manager Pep Guardiola continues to make high-profile signings.
9. Liverpool FC — 51 million followers
Followers (millions):
Facebook: 31.9
Instagram: 8.6
Twitter: 10.5
Mohamed Salah the "Egyptian King" of Liverpool has 19.3 million followers on Instagram.
"Salah is now considered the most famous person in Egypt," Egyptian doctor and Salah mega fan Michael Wagdy told The Sun.
"He has now become an idol for the people… we now wait for any match for Liverpool and you can't imagine the happiness that occurs when he scored."
8. Juventus — 55.1 million followers
Followers (millions):
Facebook: 34.6
Instagram: 14.3
Twitter: 6.2
Cristiano Ronaldo's €100 million transfer to Juventus had an unsurprisingly monumental effect on Juventus' social channels.
Ronaldo, who is the second most-followed person on the whole of Instagram (just one million behind Selena Gomez at the time of writing), added more than 400,000 followers onto Juventus' main and English Twitter pages, as well as in excess of 1.4 million on Instagram and 400,000 on Facebook, according to Football Benchmark.
Ronaldo's post confirming his move to Juventus quickly became the 4th most-liked Instagram of all time.
7. Paris Saint-Germain — 55.8 million followers
Followers (millions):
Facebook: 35.2
Instagram: 14.2
Twitter: 6.4
The French team won a domestic quadruple last season, just nine months after flexing its financial muscle as it signed Neymar for a world record transfer fee of £200 million.
The Brazilian striker will have represented a boon to the team's social media standings as well as their goal-scoring prowess, as he boasts over 100 million followers on Instagram alone.
6. Arsenal FC — 63.3 million followers
Followers (millions):
Facebook: 37.8
Instagram: 11.8
Twitter: 13.7
Arsenal dropped out of the top five most popular clubs on social media this year after failing to qualify for this season's Champions League tournament.
The club does benefit from French wing-back Hector Bellerin, though, who is basically a part-time model and posts pictures of himself at events like the GQ Awards and London Fashion Week on Instagram.
5. Bayern Munich — 65.7 million followers
Followers (millions):
Facebook: 47.6
Instagram: 13.6
Twitter: 4.5
Bayern Munich is up one place since February last year, topping London side Arsenal.
The German side will have received a boost from signing Colombian midfielder James Rodriguez, who boasts almost 40 million followers on Instagram.
Unlike its top rivals in Spain, Bayern Munich runs its Twitter page in its native language — even though its Facebook page posts in English — which may account for its low following on the micro-blogging site.
Their English Twitter account has over 900,000 followers.
4. Chelsea FC — 72.2 million followers
Followers (millions):
Facebook: 47.7
Instagram: 12.4
Twitter: 12.1
Stamford Bridge continues to attract the biggest celebrity spectators (Will Ferrel popped in to congratulate Eden Hazard last year) and where celebrities go, social media follows.
It may also surprise you to learn that Brazilian centre-back David Luiz has over 18 million followers on Instagram.
3. Manchester United — 114.8 million followers
Followers (millions):
Facebook: 73.5
Instagram: 23
Twitter: 18.3
Manchester United may have topped the Money League for two years running, but it's still a long way off breaking into the top two in terms of social media following.
Last season saw United lose one of its biggest stars, Zlatan Ibrahimovic, who has almost 35 million followers on Instagram as he migrated over to the US to join LA Galaxy.
Their biggest star in terms of social following, Paul Pogba, now has a World Cup winners' medal to his name.
2. FC Barcelona — 190.4 million followers
Followers (millions):
Facebook: 102.7
Instagram: 58.8
Twitter: 28.9
Barcelona has a further 5.6 million followers on its Catalan account and a further 13.6 million on its Spanish one.
Lionel Messi is the third most-followed football player on Instagram after Neymar and Ronaldo, boasting 97.5 million followers on the platform.
1. Real Madrid C.F. — 201.9 million followers
Followers (millions):
Facebook: 109.2
Instagram: 62
Twitter: 30.7
Despite losing Cristiano Ronaldo this summer, Real Madrid is the biggest football club on social media right now and the only club in the list to top 200 million followers across all platforms.
"Los Blancos" have gained over 40 million followers since February last year, toppling their El Clasico rivals Barcelona for the top spot.