Behind every great football team is a world-class goalkeeper.
Without one, no side can realistically label themselves as 'complete'. Just look at the change in Liverpool's fortunes when they brought in Alisson Becker to replace Loris Karius.
A great goalkeeper can win games almost single-handedly and the very best are often held in the highest regard by the clubs they have starred for.
Fans over on Ranker have been voting for the greatest goalkeeper in football history and it's fair to say the top 30 will spark A LOT of debate.
The process of up-voting and down-voting has seen a few suspect entries creep up alongside some of the most legendary 'keepers to have stepped out onto the hallowed turf.
30. Jorge Campos
Perhaps not the greatest 'keeper of all-time, but certainly one of the most unique. Campos is renowned for his ability to play either in goal or - get this - up front.
The Mexican would sometimes start club games between the posts and finish up as a striker, scoring 34 goals across his career. Not a bad return.
29. Pat Jennings
One of the greatest goalkeepers in the history of English football, starring for Watford, Tottenham and Arsenal.
He also enjoyed a 22-year international career with Northern Ireland.
28. Claudio Taffarel
A Brazilian legend, earning 101 caps for the Selecao and helping the nation lift the World Cup in 1994.
His international career was actually far better than his club one.
Arguably the greatest Brazilian goalkeeper of all-time and the first from the country to be nominated for the Ballon d'Or.
The man Ederson and Alisson aspire to be!
26. Fabien Barthez
In his prime, Barthez was an absolute beast and he shares the record for the most World Cup clean sheets with Peter Shilton.
But after his error-filled spell with Manchester United, the Frenchman probably shouldn't be making the top 30.
25. Harald Schumacher
Most famous for clattering and seriously injuring Frenchman Patrick Battiston at the 1982 World Cup.
The German was a very good 'keeper in his hay day, but probably doesn't belong in the top 30.
24. Marc-Andre ter Stegen
The Barcelona star is one of the best in the business and has been for some years.
But ahead of Blaugrana legend Victor Valdes (34th) already? It's certainly an interesting one.
23. Keylor Navas
A key man in Real Madrid's Champions League treble, but one of the 30 greatest goalkeepers of all-time?
Top-class in bursts, but far from a legendary presence between the sticks.
22. Guillermo Ochoa
A baffling inclusion.
A great 'keeper on his day, a loveable character and the proud owner of THAT performance versus Brazil at the 2014 World Cup, but the Mexican is far from a great of the game.
21. David Seaman
Now we're talking. One of the greatest to don a pair of gloves, an absolute man-mountain for both Arsenal and England.
You could certainly make a credible case for Seaman being far closer to the top 10.
20. Peter Shilton
They don't make 'em quite like Shilton anymore. To perform like big Pete did at the 1990 World Cup at the age of 40 is worthy of a top 20 place alone.
Aside from that memorable campaign, he was an absolute superstar for Leicester, Stoke, Nottingham Forest and many other English clubs.
19. Rene Higuita
A revolutionary figure between the sticks, one who kickstarted the trend of 'keepers taking more responsibility on the ball. His antics actually saw the creation of the 'back-pass rule', which is also known as 'Higuita's law'.
Plus he once saved a ball while doing a scorpion kick, so we feel 19th place is pretty deserved for such a unique character.
18. Jean-Marie Pfaff
A very good goalkeeper for Belgium during the late 1970s and 1980s, plus he even enjoyed a decent spell at Bayern Munich between 1982 and 1988.
However, what Pfaff is doing at 17th is beyond us.
17. Tim Howard
Howard ahead of Seaman and Shilton? Do us a favour.
The American was certainly good, but that's all. To put him ahead of two of the greatest of all-time is just not on.
16. Jens Lehmann
Part of the Arsenal 'Invincibles' and the proud owner of the most consecutive Champions League clean sheets (10).
But ahead of Seaman? Surely not.
15. Hugo Lloris
A World Cup-winner and a fine shot-stopper, but few top-class goalkeepers have ever been more prone to errors than Lloris.
The Tottenham man really shouldn't be sitting ahead of so many legends.
14. Thibaut Courtois
Now that he's found his feet at Real Madrid, Courtois is looking like a legend-in-the-making once again.
But with so much of his career to come, you can't be ranking Belgian 14th just yet.
13. Michel Preud'homme
Regarded by many as one of the finest of his generation and the Belgian was named as the best goalkeeper at the 1994 World Cup.
Thirteenth seems a tad generous, though...
12. Sepp Maier
Hard to argue with this one. A Bayern Munich icon and one of the greatest players to ever hail from Germany - which is saying something.
Maier was named Die Mannschaft's 'Goalkeeper of the Century' and helped his country win the 1974 World Cup.
11. Dino Zoff
Again, impossible to argue with this. If anything, the Italian great should be higher.
Zoff is the oldest player to ever win the World Cup (40 years, 4 months and 13 days) and holds the record for most consecutive minutes without conceding at a major international tournament (1142 mins).
10. Gordon Banks
England's greatest ever goalkeeper and the owner of possibly the finest save ever made.
Honestly, we still don't know how he clawed away that header from Pele.
9. Petr Cech
Due to his indifferent spell with Arsenal, Cech is almost underrated these days.
8. Edwin van der Sar
The winner of 26 major trophies and the oldest man to lift the Premier League during his days with Manchester United, the Dutchman is a bonafide legend.
Van der Sar still holds a football world record as well after going 1311 minutes without conceding during the 2008/09 season.
7. David de Gea
Ahead of Van der Sar, Banks, Zoff and many other legends?! Absolutely ridiculous.
De Gea has been brilliant for Manchester United, but the seventh best 'keeper in football history? No way.
6. Peter Schmeichel
Many regard the Dane as the greatest of all-time in his position, so to see him at number six is a big surprise.
At least he's ahead of De Gea, though!
5. Lev Yashin
The Russian and Dynamo Moscow icon is considered by man to be the greatest goalkeeper of all-time and he's the only 'keeper to win the Ballon d'Or, a feat which he achieved in 1963.
So who're the four men the fans believe to be better?
4. Oliver Kahn
The German giant is first up and his CV isn't too shabby.
A serial trophy winner with Bayern Munich and the winner of the Golden Ball at the 2002 World Cup, Kahn at fourth place is certainly not a bad shout.
3. Manuel Neuer
Like Higuita, Neuer - as well as being an outrageously good 'keeper - has redefined the role.
He's ushered in the era of goalkeepers being able to pass as well as some midfielders and without him, football in the present day would probably look a lot different. A deserved third place.
2. Iker Casillas
World Cup, Champions League, La Liga, European Championship, you name it and Casillas has won it.
His trophy haul says a lot and the rest of the talking was done by his brilliance on the pitch.
1. Gianluigi Buffon
A controversial number one. Buffon is a legendary figure of the game, but the greatest? That's certainly up for debate.
Especially when you look at the litany of elite superstars behind him...
There is, of course, a modern bias to the top 30.
The likes of Shilton, Banks, Zoff and Yashin should certainly be mixing more with the modern stars in the top 10.
But that's the beauty with these sort of rankings, there will never be one that satisfies everyone!
- Ranking 15 of the most humiliating individual performances ever
- The 50 greatest derbies in football throughout the world
- Video goes viral of Diego Maradona dominating at the 1986 World Cup