We can't pretend that the full-back positions are the most important on the football field―that honour will always go to the players who score the goals and grab the headlines―but a good one is often hard to find.
A left-back who is strong defensively and good coming forward can be worth their weight in gold, as they contribute in defence as well as getting involved in their team's attacking moves.
But just who are the best around in the position?
Here, in no particular order, we look at 10 of the best:
If players are judged solely on what they've won, then Ashley Cole must be up there with the best of them.
The Englishman may have angered many with the manner of his move from Arsenal to Chelsea in 2006, but his career has undoubtedly benefited from it.
Cole has now won three Premier League titles (two of them with Arsenal), a record seven FA Cups (three with the Gunners), the Champions League and the Europa League, as well as picking up 103 caps for England. He is also one of just two players―the other being Nicolas Anelka―to win the league and FA Cup double with two different teams.
A dependable presence on the left side of defence, the 32-year-old combines strong defending with a threat coming forward which, although it doesn't see him grab many goals, does make him a strong presence in any team.
The blossoming of Bayern Munich as a European force has coincided with the emergence of their Austrian left-back David Alaba.
Initially regarded as a midfielder, the 21-year-old Alaba has become a regular on the left side of the Bayern defence, and he played a key role in the club's 2012/13 Champions League win; scoring with a long-range strike just 25 seconds into the quarter-final against Juventus.
Now under the tutelage of Pep Guardiola, Alaba will only improve in the seasons ahead.
His development will be a joy to watch.
It could be said that the distinctive Marcelo struggled initially at Real Madrid following his arrival from Brazilian football in 2007, but he's since gone on to be a huge hit with Bernabeu fans.
It was Jose Mourinho's arrival in Madrid in 2010 which was arguably his turning point, as the Portuguese coach allowed him to develop his game at left-back rather than on the left side of midfield.
He responded by reaching a level of consistency that many thought wasn't possible, and he stayed in the side until injury decimated his last campaign.
Now the first-choice for Brazil at left-back, it can be easy to forget that Marcelo―who has scored 17 goals for Real―is still just 25, and has plenty more years ahead of him.
It is largely down to the form of Madrid rival Marcelo that the somewhat underrated Felipe Luis can only point to four Brazil caps, but that doesn't take away from his quality.
A former youth player at both Ajax and Real Madrid, Felipe Luis didn't allow his early frustrations in the European game to get him down, and he succeeded at Deportivo La Coruna for four seasons before his move to Atletico Madrid in 2010.
The energetic 27-year-old has been a virtual ever-present threat down the left flank for Atletico for the last three seasons, winning the Europa League and Copa Del Rey in that time.
A move to one of the really big boys could beckon, but right now he's happy where he is.
Now 32, there is a pretty convincing school of thought which suggests that Patrice Evra had his best season for Manchester United in the last campaign.
The 48-times-capped Frenchman was a constant source of energy down the left flank, even adding four goals to more than double his previous career tally for the Old Trafford club, having joined in 2006.
Evra won his fifth Premier League title at the end of the campaign, and enters David Moyes' first season at the club as a key figure and regular captain of the side.
He might just be getting better with age, something the United fans will be delighted to see.
If the Spain team which won Euro 2008 and the 2010 World Cup had any weaknesses―a big if―then perhaps it was in the left-back position.
That has all changed now though with the emergence of Jordi Alba, who at times resembles a one-man left flank.
His performances at Euro 2012―where he scored in the final against Italy―alerted the world to the quality he'd shown regularly over four years at Valencia, and a big-money switch to Barcelona followed.
He's predictably excelled at the Nou Camp, slotting into the side as if he's been there for years and almost single-handedly demonstrating what it takes to be a modern-day full-back.
Quite simply, he never stops.
Portugal's Fabio Coentrao has perhaps suffered due to his versatility at Real Madrid, where he has played in a variety of different positions ever since a big-money move from Benfica in the summer of 2011.
Injuries and the form of Marcelo have ensured that it has rarely been plain sailing for Coentrao in Madrid, but he is still the top-quality left-back who shot to prominence at Benfica and impressed for Portugal at the 2010 World Cup and and Euro 2012.
Maybe the 25-year-old will need another move to demonstrate his quality again, but there are likely to be managers queuing up to take him.
He's too good a player for them not to be.
He's only 20 and so French youngster Lucas Digne's inclusion on this list might be seen as premature by many, but he's certainly very promising.
Promising enough, in fact, for Paris Saint-Germain to spend €15m to bring him to the club from Lille this summer.
Quick, athletic and good coming forward, Digne looks to have all of the requirements of the modern full-back, and even weighed in with three goals for Lille last season.
Still yet to be capped for France at senior level, it only looks to be a matter of time before Digne succeeds the likes of Evra and nails down a position in the national team. He could then be capable of holding onto that spot for years to come.
A left-back who can regularly contribute to the goals for column is a special thing to have, and Everton have one who remains a key figure for them.
The Merseyside club have relied upon Leighton Baines ever since his move to his boyhood heroes from Wigan Athletic in 2007, with the 28-year-old notching 22 goals for the Goodison Park outfit since then.
Possessing terrific crossing ability, an accurate free-kick and a nerveless penalty, Baines is unfortunate to be behind Cole in the England pecking order, although he's still managed to pick up 17 caps, and is a target of former boss David Moyes at Manchester United.
England can only rue the fact that they don't have this level of quality backup in all positions.
Although picked as Bayern Munich's regular right-back as the emerging Alaba plays on the left, the metronomic Philipp Lahm switches to the other side when he plays for Germany, who he captains.
Amazingly still only 29, Lahm seems to have been around forever, with his enduring appeal perhaps drawn from the fact that he regularly makes an impact in major tournaments.
Cutting inside onto his right foot, Lahm had the whole of Germany celebrating when he scored the opening goal of the 2006 World Cup from distance in a match against Costa Rica. He also scored the winner in the Euro 2008 semi-final and found the net in the quarter-final at Euro 2012.
An ever-present threat going forward, the diminutive Lahm combines pace, power and excellent tackling abilities to mark himself out as one of the elite footballers around today.
In any position.