Manchester City vs. Barcelona: Key Players in Champions League Clash of Titans

European powerhouse Manchester City host Barcelona on Tuesday at the Etihad in a critical Champions League round-of-16 matchup.

While both sides are a who's who of talent and prestige, there are a few key players who are capable of turning the tide in their side's favor.

As far as motivation is concerned, this City squad will be determined to prove itself and make a deep run after a number of disappointing exits in recent years. Barcelona, on the other hand, will be seeking a return to the summit for the first time since their legendary team won the competition in 2011.

City's 4-1 aggregate defeat to the Blaugrana last year will be fresh in the minds of everyone involved, though for different reasons.

"At this stage of the competition when you play over 180 minutes it is very important to win the first game. After that, try not to concede goals here at home," said manager Manuel Pellegrini during Monday's news conference, per ESPN.

Suggesting a focus on defensive solidity, the manager went on to note a scoreless draw would be preferred to a level shootout.

Here are the key players (based on Who Scored's probable lineups) who will decide Tuesday's Champions League clash of titans.

Dani Alves

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The Brazilian wing-back was invaluable in last year's matchup, adding clinching goals in both legs of the tie. This year, however, his world-class displays of equal parts attack and defense have become few and far between. Simply put, he's not the consistent player he once was.

Add Saturday's devastating loss to Malaga to the equation, and Alves starts to look frighteningly unreliable. His awkward back pass in the early minutes of that La Liga match led to the only goal of the game, and Barcelona were never able to recover.

If the Blaugrana couldn't bounce back from a defensive lapse at home against Malaga just a few days ago, then going down early at the Etihad could prove disastrous.

However, outside of the less-dynamic Adriano, manager Luis Enrique simply does not have a seasoned backup in Alves' position ready for a crucial game. In order for Barcelona's system to work, Alves will have to be as astute on defense against David Silva and Samir Nasri as he is threatening in attack.

Look for the Brazilian to be more focused on Tuesday than he was against Malaga. He may be past his prime, but Alves can still be a game changer when he's called upon for the big occasion.

Yaya Toure

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Yaya Toure is ineligible for this match, as he is serving the third and final game of his suspension after a receiving a red card in the group stages, but his absence may be felt in a less intuitive (but just as significant) way.

Without Toure in the Premier League this season, City have recorded just one win, five draws and one defeat. His return this weekend reminded us of the power of his influence, as City coasted to a 5-0 thrashing of Newcastle at the Etihad.

Without Toure in the Champions League, however, the Sky Blues can be more optimistic. The Ivoirian's two absences in the group stage were both wins for City, indicating that his teammates are certainly able to draw on their own wealth of talent when Champions League elimination is looming over their heads—as it is on Tuesday, in a very real sense.

While Toure's absence in the midfield will be felt, it could also have a positive, sobering effect on his teammates, who realize they will have to be more focused and imposing if they hope to get a result.

Without their anchor in midfield, City may give up just floating in the CL and actually try to fly.

Luis Suarez

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Despite trading his Reds kit for Catalan colors this summer, Luis Suarez will not have been forgotten in England. The all-time leading single-season scorer in the English Premier League showcased unpredictable runs, close control and deadly finishing that was the stuff of nightmares for every defender in the league.

Though Suarez failed to score against City in two league meetings last season, his presence was more than enough to draw defensive cover and provide space for his teammates to bag goals of their own.

Now that former teammates Raheem Sterling and Daniel Sturridge have been replaced by living legends Lionel Messi and Neymar, City's defense will just as fearful (if not considerably more so) of focusing too much attention on the Uruguayan.

Suarez has provided his Barca teammates with 11 assists in all competitions so far this season, per Goal.com. So whether he’s scoring them or setting them up, the ex-Liverpool forward will be a constant threat as he continues to jell with two of the world's best against City.

Eliaquim Mangala

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The 24-year-old French center back will have his work cut out for him against Barca. Mangala has the size, strength and general physical assets to go toe to toe with the best of them, but does he have the diligence to maintain City's defensive solidarity against Barca's front three?

While Vincent Kompany is capable of being the level-headed rock City need in defense, his center-line partner Managala sometimes breaks the line to maraud forward into the midfield to try to cut out an early pass.

Given Pellegrini's defensive mindset going into the match, it's likely the French international will be repeatedly reminded to stay behind the protective midfield wall of Fernandinho and Fernando at all times to ensure double lines of defensive coverage from the midfield on back.

However, all it takes is one lapse—like jumping out of line to try to cut out a pass in the midfield—to afford Barcelona enough space behind the defense to score that all-important away goal.

Will Mangala stick to the script or will he flub his lines? The result will be riding on his performance.

Ivan Rakitic

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All signs point to Rakitic starting this critical away leg. His exclusion until the 63rd minute of the Malaga match was clearly an attempt on Luis Enrique's part to rest the midfield pass master. He is also Barcelona's only reliable long-distance shooter in midfield, and that dynamic will be sorely needed against a packed City defense.

Enrique would have long suspected City would keep one foot planted firmly at home in the first leg of this tie to protect their away-goals advantage. For this reason, he will undoubtedly call upon Rakitic to provide a midfield threat with his distance shooting so City will be forced to defend him a little farther out.

By looking to shoot from outside the box, the Croatian will both keep Joe Hart honest and tempt defenders like Mangala to try to close him down when he shirks his midfield mark. This combination of factors, described in more detail here, will afford his teammates the crucial space they need to play their trademark one-twos into the box to get a close shot on goal.

Not unlike Suarez, Rakitic could decide this match not so much by what he does but rather by the threat of what he might do.