Goaltending in soccer is in many ways the most crucial position, despite not always being the flashiest. The netminder is the final line of defense for a team, but it's also essential in organizing the defense.

The Champions League will be a Madrid derby and is slated to feature two dangerous attacking sides that will undoubtedly rely on their respective goalies to save them on multiple occasions. The two goalies that will be in between the pipes have been recognized as the best of their time at different time periods in their careers. Here is how the two goalies matchup against one another.

For the past decade, Real Madrid's Iker Casillas, 32, has been considered the best goaltender in the world. The Spaniard, also known as "San Iker," has the knack for making huge reflex saves and is also a born leader that helps organize the defensive line in front of him. For years, Casillas' position with Madrid was unquestionable, but the keeper ran into some trouble under manager Jose Mourinho and wound up riding the pine during the end of the 2012-13 season. The arrival of Carlo Ancelotti at Madrid this past summer was supposed to restore Casillas to his position as Madrid's top guy, but instead he was forced to settle for a backup role with the squad and was only given the chance to lead Madrid in the Copa del Rey and Champions League.

Casillas has acquitted himself extremely well and has made some dynamic saves at key moments. Among his big saves of the tournament was a big stop on Julian Draxler in the Champions League round of 16 first leg at Schalke that could have tied the score at 1-1 and potentially changed the complexion of the match. Another huge save for Casillas came against Bayern Munich in Madrid with the score at 1-0. A goal on that shot by Mario Gotze could have left Madrid at a disadvantage heading into Munich for the second leg.

Casillas has never lost a single match against Atletico Madrid and was the keeper in net during the team's 5-0 aggregate win in the Copa del Rey semifinals. He has conceded a total of nine goals in 12 Champions League matches thus far. One of the defining moments of Casillas' career came back in 2002 during the Champions League when he replaced an injured Cesar Sanchez and made key saves to help the club lift its ninth Champions League trophy. He has also won the Copa del Rey twice and was the netminder in goal for Spain during the World Cup final in 2010 and two Euro Cup finals in 2008 and 2012; in 2010 final he made a wondrous save on a one-on-one with Dutch Arjen Robben that ultimately saved the game for Spain. Those high-pressure experiences should serve him well in this final.

If Casillas has any weakness, they are usually attributed to his aerial abilities. At 6-foot-1 he is a relatively "short" keeper and will sometimes find himself out of position on aerial crosses or corners.

Atletico Madrid's 21-year-old keeper Thibaut Courtois is currently being hailed as the greatest goalie in the world, and his body of work over the last few years certainly makes his case rather well. He is a huge goalie, 6-foot-6, making him terrific at handling aerial plays. He is also brilliant at making reflex saves, including one that Chelsea manager Jose Mourinho stated was the game changer in the semifinals between the two sides.

"I think the difference was one minute in the second half, where Atlético goalkeeper makes an impossible save from John Terry's header, and instead of 2-1 to Chelsea, a few seconds later a penalty," the Portuguese manager said about the goalkeeper's stop.

Courtois was also brilliant against AC Milan during the first leg and helped his team walk away from Italy with a 1-0 win. Courtois and Madrid did not lose a single game in the UCL this season, and he only conceded a grand total of six goals in 12 matches.

Courtois' only major weakness is in his long-range passing. This is also something that Casillas shares. Another disadvantage for the keeper is his lack of experience in comparison to his counterpart. While Courtois was huge in leading Atletico past Real Madrid last season in the Copa del Rey final and also led the team to the Europa League trophy, he has arguably never been in such a big final thus far.

So who has the edge in goal? 

From a technical perspective, Courtois has no major flaws and has youth on his side. He has a few finals to his name, but Casillas far outstrips his experience in major matches. This could work in favor of Los Blancos as the keeper's demeanor can help relax or create more anxiety for a team's backline. If Thibaut holds it together in the big game, as he normally does, then Atletico has a slight advantage in net. However, do not overlook Casillas' record against Atletico (he has never lost against them) or his ability to come up big in huge matches. Otherwise, slight edge to Atletico Madrid.