UPDATE: Barcelona 2-2 Chelsea, Final Score

For the first 30 minutes, everything was normal at the Camp Nou. Chelsea were playing with 10 men behind the ball and Barcelona were trying to break them down. The Blaugrana had some solid chances, but the Blues had their defense organized and didn't look terribly bothered. The last 15 minutes of the first half were absolutely nothing like the first 30.

Sergio Busquets leveled the tie for Barcelona in the 33rd minute, which was followed up by a sending off for John Terry. Shortly afterwards, Andres Iniesta scored, which should have all but ended the tie. Improbably, Chelsea found a way to score on the counter with an absolutely brilliant goal by Ramires, and inexplicably, the Blues are going through as it stands. Barcelona leads 2-1 on the night at halftime, with the tie locked up at 2-2 and Chelsea ahead on away goals.

Before things went absolutely insane, there were two injuries to central defenders that looked like they were going to be the game's biggest stories. Gary Cahill injured his hamstring in the 7th minute and attempted to continue, but could not. He was replaced by Jose Bosingwa in the 12th minute, a substitution that moved Branislav Ivanovic to the center of defense.

In the 17th minute, Didier Drogba, Victor Valdes and Gerard Pique all collided with Pique getting the worst of the challenge. The Barcelona defender attempted to continue, but like Cahill, was not able to do so. Unlike Cahill, there's a good chacne that he played for five minutes with a concussion. He was replaced by Dani Alves in the 25th minute.

Barcelona got on the board 33 minutes in through Sergio Busquets, and he couldn't have had a simpler finish. The start of the move was a Barcelona corner kick that was easily cleared away by Chelsea, but their defense seemed to fall asleep after the clearance. Dani Alves got onto it and played the ball wide for Isaac Cuenca, who sent a cross into the box. It went through everyone and found Busquets, who scored a tap-in to level the tie 1-1.

Things got much, much worse for Chelsea four minutes later when their captain and only true central defender on the pitch, John Terry, got himself sent off for a knee to the back of the leg of Alexis Sanchez. The referee didn't see the incident off the ball, but he was alerted to it by his linesman and had no choice to send off Terry for this obvious bit of foul play.

Seven minutes later, in the 44th minute, Andres Iniesta appeared to put the nail in Chelsea's coffin with this goal, which made it 2-0 to Barcelona on the night and 2-1 on aggregate.

The finish was nice, but the assist by Lionel Messi was the real magic here. Even though the pass was a short one, you can count on one hand the number of players who can consistently play a pass that precise to hit a teammate perfectly in stride as consistently as Messi executes that pass. Up a goal and a man, Barcelona appeared to have the game in the bag. Then, just like they were in first half stoppage time in the first leg, they were undone by the pace of Ramires and the skill of Frank Lampard.

The obvious difference between this goal and Drogba's last Wednesday is that Ramires didn't require any help. The goal was created in a similar fashion and for similar reasons -- Barcelona's defense getting too aggressive against a speedster like Ramires -- but the finish was probably better than any cross he's ever played in his life. To chip Victor Valdes like that while he's standing straight up is astonishing.

With Chelsea ahead on away goals and down a man, it's not terribly clear exactly what the two managers are going to do in the second half. Obviously, Chelsea will be defensive and Barcelona will attack, but the entertainment will be in exactly how they attempt to execute those strategies, and exactly how much Chelsea looks to break out on the counter, if at all.

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We'll have live coverage throughout the game in our Barcelona vs. Chelsea, 2012 UEFA Champions League StoryStream. For more on the two teams, head over to Chelsea FC blog We Ain't Got No History and FC Barcelona blog Barca Blaugranes.