This year’s UEFA Champions League final needs little selling. Real Madrid and Juventus have been, indisputably, the two best sides in Europe all season, lending Saturday’s collision in Cardiff an air of prestige that few finals in the past decade could match.

Both held off challengers to triumph domestically. Both boast showpiece scalps from the Champions League quarterfinals (Juve over Barcelona, Real Madrid over Bayern Munich). And both will line up with mega-talents that could feature for just about every club in the world.

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Not long ago, Real Madrid was in Juventus’ position. Los Blancos went over a decade between European crowns – and eternity for the lavish-spending tentpoles of the world game – until finally winning their 10th in 2014, followed by an 11th last season.

Juventus, meanwhile, hasn’t won the Champions League since May of 1996, weeks before Zinedine Zidane arrived for a five-year star turn in Turin. Zidane is now manning the touchlines for Real Madrid and looking to extend this incredible run, while Massimiliano Allegri looks to restore glory to the Old Lady and Italian soccer as a whole.

What will be the keys to doing so?

Real Madrid front line vs. Juventus back line

Each unit can lay convincing claim to being the best in the world at what they do, so the fact they’re going against each other makes this final all the more sumptuous. Cristiano Ronaldo headlines the planet’s foremost attacking contingent, with 40 goals and 11 assists across all competitions, and he’s capably supported up top by Karim Benzema.

A decision lies with Zidane over whether to start Gareth Bale or Isco, with the latter playing a vital role in Real Madrid’s late-season surge while the former has spent a lengthy spell on the sidelines with an ankle injury. If Zidane does start Isco (and common sense dictates he would), it will be curious to see if he plays at the top of the midfield in a 4-4-2, or if he plays out wide atop a 4-3-3.

That depends on how Real Madrid wants to attack Juventus’ defensive stronghold, which has allowed a paltry four goals in 12 Champions League fixtures this campaign. Do you try to break down the central spine of Giorgio Chiellini, Leonardo Bonucci and goalkeeper Gianluigi Buffon with Isco as a playmaker serving direct balls in to Ronaldo and Benzema? Or do you try to stretch the back line out wide and look for gaps?

Either way, it will be as difficult a test as Real Madrid has faced all season. For all of Buffon’s incredible success, the 39-year-old has yet to win the Champions League, and he and his defensive teammates would love to be the driving force behind doing so.

Dani Alves vs. Marcelo

While Juventus is tactically flexible, it would seem prudent of Allegri to line up with four defenders at the back instead of a 3-5-2 against Ronaldo and company. In either case, Dani Alves should run Real Madrid left back Marcelo ragged. And vise versa.

Both Brazilians love to get forward, and their abilities to do so add another dimension to each side. Alves has discovered a fountain of youth and proven effective as both a right back and wing midfielder, and he caught this golazo against Monaco as cleanly as one could dream.

Marcelo, meanwhile, has left many a back line exposed with his passing and movement, and he is comfortable playing 1-2s with those further up the pitch. It’s just another wrinkle to which Juventus will have to pay added attention, and that makes Real Madrid even more dangerous.

Real Madrid defenders vs. their own temperament

It also makes them more vulnerable. In a side where virtually everyone is a scoring threat, and a willing scoring threat at that, you can leave yourself prone if you’re not careful.

That won’t do against Gonzalo Higuain and Paulo Dybala, Juventus’ in-form strike tandem that’s netted a combined 44 goals this season. A former Real Madrid man himself, Higuain will be looking to erase demons of major finals past, although his failure to convert straightforward chances on those occasions came while wearing an Argentina shirt.

Dybala, meanwhile, is looking to give Argentina further impetus to call him up on a more consistent basis. The 23-year-old has proven to be particularly adept at creating scoring chances and wreaking havoc, so Real Madrid’s defenders will have to keep a level head and stay alert.

Except that’s not how they really do things. Sergio Ramos, to borrow a line from a fellow FC Yahoo contributor, is as liable to get sent off as he is to score a late winner, while Pepe has his own history with hot-headed card accumulation. Raphael Varane’s inconsistency has left him dangling in the winds of recent transfer markets, and though Nacho has been a steadying presence this season, he’s never played on a stage like this.

Add in the free-wheeling Marcelo, the unconvincing Danilo and the demons-ravaged Keylor Navas in goal, and Real Madrid’s defending could be an adventure at the Millennium Stadium.

Casemiro vs. the world

Of all the players in both squads, Casemiro might play the biggest role in Saturday’s final.

All of Real Madrid’s attacking talent can operate with the impunity it does because the Brazilian defensive midfielder plugs so many leaks. His positioning is immaculate, and his self-awareness is largely unmatched. He’s tasked with making tackles and dirtying things up for opponents going forward, but he does it with an acute sense of judgment, having accumulated only 13 yellow cards across 33 appearances in the Champions League, La Liga and Copa Del Rey this season.

Casemiro is also a very good passer, and he’s pretty much the only player in Real Madrid’s first team who can fill the role that he owns. Zidane has known this for awhile and openly supported the 25-year-old even when higher-ups at the club did not. Such faith has paid off as Casemiro protects a back four that loves to flirt with responsibility.

Juventus will test that ability on Saturday, and figures to be patient in doing so. The Italian side completes more passes in its own half than Real Madrid, with the likes of Miralem Pjanic and Sami Khedira probing and looking for openings before bursting the attack forward. That only enhances the need for a reliable shield like Casemiro in the opposite half.

And if Juventus proves impossible to break down up close, Casemiro has shown an adeptness at long-range strikes, namely against Napoli earlier this season.

It’s yet another way for either team to provide a moment of magic in what promises to be one of the best Champions League finals we’ve ever seen.

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