Chelsea vs. Barcelona: Key Battles to Decide Champions League Semifinal 1st Leg

When Chelsea and Barcelona squared off in the 2008-09 Champions League semi-final, Barcelona were not yet the great dominating force that they are known to be today.

Pep Guardiola was in his first year as Barca manager, and had Andres Iniesta not scored a late winner deep into injury time in a highly controversial match, Chelsea would've progressed to the Champions League final for a rematch against Manchester United.

Barca would have had to wait until 2010-11 to secure the Champions League with Guardiola, and the entire course of Barca's history under Guardiola could've been altered.

But all that's history. Today, the two teams in this semi-final find themselves in very different places from where they were three seasons ago.

Barcelona are by consensus recognized as the great team in world football, while Chelsea have struggled all year and remain outsiders in the race for a spot in the top four in the English Premier League.

However, one should not underestimate Roberto Di Matteo's influence at Chelsea since taking over as manager. Chelsea are firmly in the race for fourth place in the EPL, and completed a remarkable comeback vs Napoli in the Champions League to stay in the competition.

In the FA Cup, they've made it to the final, recently demolishing a good Spurs side five goals to one.

Barca are definitely favorites in this matchup, but Chelsea could surprise Barca given the excellent form they've been in lately. Here are the big matchups that'll decide which team fails or succeeds in its bid to make the Champions League final in Munich.

Ramires vs. Adriano

Adriano has done a decent job of replacing Eric Abidal as Barcelona's left full-back. Nevertheless, when compared to the likes of Gerard Pique, Carles Puyol and Dani Alves, he's clearly Barca's weakest link in defense.

Juan Mata has traditionally been Chelsea's right winger of choice this season, but recently Roberto Di Matteo has shown a preference to play Mata as the team's central orchestrator, with Ramires on the right flank and Salomon Kalou on the left.

Ramires is and has always been known for his undeniable stamina. He's got a decent amount of pace and trickery, but the one attribute which puts him among the best is his ability to run and run and run for 90 minutes, without ever really slowing down.

Ramires will try to utilize that stamina of his to Chelsea's advantage. If he's able to get the better of Adriano, he could be Chelsea's best hope of scoring and grabbing the advantage needed to have any hope of progressing to the Champions League final.

If Adriano is able to keep up with Ramires' pace and nullify the threat he poses to Barca's defense, I can't imagine Chelsea winning the first leg, or the entire tie for that matter. They don't have a matchup more in their favor than this one.

Andres Iniesta vs. Bosingwa

It's anybody's guess as to who'll be starting on the left flank for Barcelona vs Chelsea. Pedro, Cristian Tello, Isaac Cuenca have all played as left wingers for Barca this season, as have Cesc Fabregas, Andres Iniesta and Alexis Sanchez.

Even though there a plethora of candidates for the position, I expect that Barca will look to end this tie as a contest with a dominating performance at Stamford Bridge, and thus will start their strong players.

As such, Iniesta is who I expect will start on the left, with Messi in the center and Sanchez out wide on the right.

Bosingwa seems to have regained a lot of lost confidence under Roberto Di Matteo, but he's still not what you'd call a "reliable defender."

As such, I fully expect Iniesta to turn him inside out and create multiple goal-scoring opportunity for his teammates.

If Bosingwa can prevent this from happening, Chelsea will have taken big steps towards winning this tie. If not, expect Barca to run rampant as Iniesta carves Bosingwa up time and again.

John Obi Mikel vs. Xavi

John Obi Mikel has not once in the last three years turned in a performance in a Chelsea jersey that's left me truly impressed.

And yet, even now, in the midst of one of his worst career seasons, Mikel manages to make regular appearances for Chelsea, simply because there are no other options available.

Neither Frank Lampard nor Raul Miereles are defensive-minded enough to play Mikel's position, while Michael Essien has failed thus far to show adequate progress in his recovery from the injury he picked up this past summer.

That leaves Oriol Romeu, bought from Barcelona, but he is decidedly down the pecking order for RDM.

Mikel will face his hardest defensive assignment of the year tomorrow when he is asked to do the impossible and knock Xavi out of the flow of the game.

Should he fail, as expected, Xavi's influence will likely win the game for Barcelona.

However, if he and maybe some of Chelsea's other defenders can defy expectations and sufficiently harass Barcelona's Xavi, it may just be Frank Lampard who wins the battle of forward-focused midfielders.

Sergio Busquets vs. Frank Lampard

Hate him or love him, there's no denying that Busquets knows how to do the defensive midfielder job just right.

Busquets is an excellent passer, a good tackler, and a world-class flopper whenever he needs to be. But I won't delve into that...

If Lampard were five years younger, I might've favored him in this match, but at 33 years old, Busquets must be the favorite to have a more successful game and dominate the midfield with Xavi.

Lampard's game is all about scoring, and if he can do that, he'll have accomplished his mission, even if he's outplayed by Busquets.

Busquets will need to make sure Lampard doesn't get the space he needs to score if he hopes to nullify the veteran Englishman.

Didier Drogba vs. Carles Puyol

It's the battle of the team's two biggest (both literally and figuratively) veterans.

Didier Drogba, 34 years old, will be looking to exploit Carles Puyol, also 34 years old.

Drogba, like Lampard, Essien and Terry, is far removed from the monster he was five years ago.

But against Tottenham, Drogba rolled back the clock on his first goal and turned in an all-around top-class performance that has likely ensured him the starting spot up front ahead of Fernando Torres.

If Drogba can produce a momentum of world-class skill like he did against Gallas when the pair faced off in the FA Cup semifinal this weekend, Chelsea will be well on their way to winning the home leg of their Champions League semifinal.

However, Puyol is no Gallas, and even at 34 years old, he's as sharp and strong as ever. Drogba will find replicating his goal vs Tottenham to be a very arduous task.

Lionel Messi vs. John Terry

We close with the most important matchup of all: John Terry vs. Lionel Messi.

In 2008-09, Terry's limited pace saw him struggle to keep up with Messi, but his strength and tenacity eventually helped make sure that Messi stayed off the scoresheet, even though it was his assist that teed up Iniesta to score.

Fast forward three seasons, and the gap between Terry's pace and Messi's has only grown, as Terry has gotten slower with age and Messi has gotten faster.

If Messi scorches Terry on more than one occasion, I'd expect him to finish one with a goal, and once Messi gets on the scoresheet, you can usually bet that Barcelona will go on to dominate.

However, if Terry can prevent Messi from beating him with his pace, and hopefully get some help from Gary Cahill or David Luiz, there might be hope for Chelsea to progress from the tie.

Messi is Barca's biggest weapon, and if Terry and Luiz/Cahill can keep him from scoring, it'll be very interesting to see how Barcelona cope. I'm betting they won't be able to.