Behind every great team is an equally outstanding goalkeeper. That is why in the Champions League knockout stages, performances from the last line of defence will be vital for any side who aspires to go all the way and lift the trophy in May.
But of the last 16 teams left in the competition, who boasts the strongest keeper of the bunch? Who can rely on the man between the posts to keep goals out, driving them on to glory?
The following 16 players are the first-choice shot-stoppers for their respective teams, ordered by their quality and, above all, reliability when called into actions. The No. 1 jersey may not represent the most glamourous positions, but without a doubt it is one of the most important on the pitch.
Uruguay's No. 1 is rather underestimated as a keeper, perhaps because of some avoidable mistakes that have peppered his career. For athleticism and agility, however, the Galatasaray star has more than proven himself as a top goalkeeping talent.
A disappointing 10 goals leaked against Madrid aside, Muslera was tough to beat in the group stage, and a clean sheet at home to Juventus proved the difference as the Turks sneaked in to the last 16. Muslera now faces a tough challenge against Chelsea, but he has the raw talent to make the difference.
The group stage was a baptism of fire for Yuri Lodygin, and one in which he did not enjoy the best of fortunes. Nine goals were blasted past Zenit, who nevertheless squeaked into the last 16 by just one point.
The Russian goalkeeper of Greek heritage is highly regarded, but he now faces an even grander test in the shape of Borussia Dortmund. Can he show his best side and keep out the lethal Germans?
One of Timo Hildebrand's greatest achievements was inspiring VFB Stuttgart to the Bundesliga title in 2006/07, a success which earned him a move to Valencia.
Now comfortably installed in Schalke, the keeper has played a big part in dragging the Germans to the last 16.
Arsenal's first-choice keeper, Wojciech Szczesny, has always been a prodigy. At just 20, his skills in the net convinced Arsene Wenger that despite his age, he was up to the challenge of commanding the Gunners from the back.
Szczesny kept an impeccable clean sheet to keep out Dortmund in their own backyard during the group stages, a big feather in the cap of the Poland international. But he will have to be even better in the last 16, where the challenge of Josep Guardiola's Bayern Munich looms large.
Greek giants Olympiacos are one of the surprise sides in the Champions League last 16. That they made the cut is in large part due to the efficient keeping of Roberto, the Spanish national who was part of Atletico Madrid's march to the Europa League title in 2010.
Roberto may have conceded eight during the group stage, but six of those were yielded against French powerhouses Paris Saint-Germain. His performances against Benfica and Anderlecht helped the Greeks sneak into the next round, where they face a daunting test at Manchester United.
Victor Valdes has never been the brightest star in the Barcelona firmament. But in his final season for the team directed by Gerardo Martino, the wonderfully successful keeper will hope to go out with a bang and a third Champions League winners medal for the collection.
The goalkeeper's best attribute has been his distribution, arming the Blaugrana's offensives from the back. He has been an exceptional servant for the club, and he deserves one last glory before trying his luck in other climes.
Like a fine wine, Christian Abbiati keeps getting better with age. The Milan keeper is still going strong at the age of 36, dragging a less-than-convincing Rossoneri to the knockout rounds.
Milan's old guard face a terrific challenge in the last 16, where they take on a youthful Atletico Madrid full of verve and attacking flair. Abbiati is certain to be busy over the two legs, and his performance will be vital if the Italians are to pull off an upset.
Accepted wisdom tells us that more than any other position, goalkeepers must be experienced and of an advanced age. Alongside stars like Courtois, de Gea and Lodygin, Bayer Leverkusen No. 1 Bernd Leno is doing his best to disprove that logic and show that he has what it takes to represent a top European institution.
The 21-year-old has been a starter with Leverkusen since he was a teenager, and he looks better with every Champions League campaign he puts under his belt. Leno suffered against Manchester United during Group A, but just one goal escaped his clutches in the other four matches, and he will be key to the Germans advancing as they prepare to meet Paris Saint-Germain.
Manchester United's Spanish goalkeeper has been rather unfairly maligned during his time at Old Trafford, thanks to some glaring mistakes. But in a disappointing season for the new-look Red Devils, his goalkeeping has helped the club stay competitive in the Champions League.
De Gea conceded a miserly three goals in six games during the previous round, a record unmatched by any other goalkeeper in the competition. Question marks remain, but the ex-Atletico Madrid prodigy can keep answering them if he keeps up his Champions League form.
Equipped with almost unimaginable riches, Paris Saint-Germain in the last few years have had the luxury of almost hand-picking their team from across the world. It is a testament, then, to the formidable talents of Salvatore Sirigu that the former Palermo shot-stopper has established himself as the overwhelming first choice for the PSG net.
Sirigu has risen from Serie A mid-table to command one of the world's best teams from the back, and in the process push himself into Italy contention. The giant keeper is a reassuring presence in goal, allowing the likes of Zlatan, Pastore and Cavani to push forward with confidence.
In Manchester City's multinational dream team, it is an English star plucked from obscurity that helps keep the whole show together. England's No. 1 Joe Hart has become an integral part of the City machine, consistently impressing between the posts.
Hart may be just 26 years old, but it feels like he has been around forever for the Citizens. A crunch match against Barcelona is Manuel Pellegrini's team's reward for passing through the group stages, but their keeper has all the tools to keep out the likes of Messi and Alexis Sanchez.
Borussia Dortmund keeper Roman Weidenfeller had big shoes to fill in 2002 when he moved to the club. But over the last 12 years, he has proven an exceptional replacement for Jens Lehmann, becoming one of the best shot-stoppers in the world.
What the 33-year-old lacks in pure athleticism, he makes up in consistency and a mortal fear of making mistakes. Under his watch, BVB have turned into one of the best teams in the world, and they will be hard to beat in the knockout stages for any side.
The future certainly looks rosy for Chelsea in the goalkeeping department. Not only do they have Peter Cech (who shows no sign of slowing down), in the wings waits Thibaut Courtois, who is winning rave reviews for his displays in the Atletico Madrid net.
Even at the tender age of 21, the hulking Belgium international looks every bit a Champions League goalkeeper, using his massive frame to stop goals from across the area. Courtois was beaten just three times in the group stages, and he will further enhance his potential against Milan.
It is hard to believe that Iker Casillas spent much of last season warming the Real Madrid bench. The Merengue's improvement over the course of 2013/14 is due in a large part to the keeping of their famous son, a veteran of more than 650 appearances between the posts.
In a competitive group that included Juventus and Galatasaray, Casillas was beaten just five times, helping Madrid go through as one of just three unbeaten teams.
Petr Cech has been a talisman for Chelsea since his first day at the club, and the Czech No. 1 is well on the way to becoming a legend with the west London institution. He already has one Champions League medal under his belt, and he is keen to add to that tally.
Cech was beaten just three times during the group stage, tying him as the most formidable goalkeeper so far. Now he will have to show the same form at Galatasaray to keep Chelsea on the right track.
Bayern Munich had to make a big statement between the posts for fans to forget about club icon Oliver Kahn. But with the charismatic yet consistent Manuel Neuer, the best club in the world found the perfect keeper to spearhead their dominance.
Neuer may not possess the same dominating personality as the terrifying Kahn, but he is an all-round stopper with no visible weakness. He occasionally gets carried away with the ball at his feet, but after conceding just five goals during the group stage, he is in form and ready to fight for a second consecutive Champions League.