Barcelona and Juventus have one more game to play before all is said and done.

Usually one expects big players to have big games in big moments. Often, games do not turn on the big players, but on the unexpected sources, the so-called "X-factors."

Both teams certainly have players that can turn ties around at a moment's notice and there is no doubt that for Barcelona and Juventus, there are some players that could turn the tide. Here are both teams' X-factors in the big game.

Barcelona - Sergio Busquets

Lionel Messi, Luis Suarez, Neymar and Andres Iniesta are the players that people expect to have big games. They have championship caliber and are proven winners. They are capable of taking games on their own and thoroughly dominating opposition.

It should also be no surprise that Barcelona's defense will be relied heavily to keep a solid Juventus side at bay.

That said, there will be one battle that likely determines the tide -- Arturo Vidal vs. Sergio Busquets.

Sergio Ramos was employed as Real Madrid's holder in the Champions League semifinal, his main task to shut down the Chilean attacker.

He failed and Madrid left Turin with a 2-1 deficit that it was never able to overcome.

Vidal grates on the opposition, his creativity complemented by physicality and strength that make him a brutish force. To shut him down you have to take him down, fouling him off his game and forcing him into costly mistakes. He is not a particularly big man, but he is a strong one.

Busquets will likely be tasked with shutting down Vidal and his ability to do so would essentially stop the Italian side's attack dead in its tracks. Andrea Pirlo is still capable of making things happen, but Vidal gives Juventus another major outlet for the attack.

If Busquets wins the battle, then Pirlo becomes central to his team's attack. This might force him further up the pitch, leaving Juventus more susceptible in the heart of the pitch, the area where Barcelona does its best damage.

Juventus - Formation & Paul Pogba

Juventus will likely win this game based on how Massimiliano Allegri chooses to play his cards. He has used the 3-5-2 and 4-3-1-2 formations most this season with the former used as a tactic to flood the midfield and the latter allow him more ball retention.

Both come with their issues against Barcelona; the former allows him more pressure in the midfield but leaves him slightly more vulnerable on the flanks while the latter allows him more ball retention, but could prove ineffective against a team that does the possession game plan better.

Both formations rely heavily on Stephan Lichtsteiner and Patrice Evra's attacking and providing support and this is likely where the battle is won. Both players are capable of creating an overwhelming presence in the attacking third, often moving the 4-3-1-2 formation into a 2-3-3-2 in attack. Anyone can see the issue here however, especially with Barcelona's own Dani Alves and Jordi Alba attacking with speed down Barcelona's flanks.

The 3-5-2 often turns into a 5-3-2 in defense, providing the team with a similar template to that used by the Dutch in last year's World Cup when they took down Spain 5-1 in the opening game of Group B. But this also limits the team a bit, allowing for an extra central defender, but forcing out a midfielder in attack. Based on current form that would likely be Paul Pogba, the ultimately X-factor in this match.

If Pogba plays there will always be questions about how well he will perform. His form has been erratic due to injury and some wonder whether the youngster is able to influence the match in a positive way.

However, leaving him off the pitch keeps one of the team's more creative and dominant forces on the bench. If Vidal is shut down by Busquets, the Pogba can provide Pirlo with much-needed creative respite in the middle. That is the gamble. Will he be able to take that responsibility or will he have one of those poor performances on display in the recent Copa Itallia Final?