The Blues were in serious trouble after goals from Sergio Busquets and Andres Iniesta put Barca ahead either side of Terry’s red card for violent conduct.
But Ramires strode forward to chip the away side back ahead in the tie.
Lionel Messi hit the bar with a penalty for Barca and Fernando Torres ran clear to seal the tie in injury time.
Earlier in the week, Torres had said “the best team does not always win”. His words proved gloriously prophetic for England’s last men standing in Europe as they fought tooth and nail to scrap their way past the continent’s finest and into the final in Munich on 19 May.
That it was Torres who scored the goal after being so maligned during his time at the Blues made for the perfect ending to a famous night for Roberto di Matteo’s side.
But then, the whole game turned expectation on its head. Holders Barcelona had scored 102 goals at the Nou Camp this campaign and were unbeaten in 15 European fixtures dating back to October 2009, having won 13 and drawn two. They had scored 18 goals in five home games.
However, several factors gave Chelsea hope heading into the second leg: their last three visits to the Nou Camp had each ended in draws, Real Madrid had torched the myth of Barca’s home invincibility on Saturday, and the Blues brought with them the protection of Didier Drogba’s first-leg winner.
Chelsea v Barca facts
Chelsea are now unbeaten in their last four matches at the Nou Camp, having drawn all of them.
Lionel Messi remains without a goal against Chelsea in eight matches, the most games he has played against a single opponent without a goal.
Fernando Torres becomes the 19th player in CL history to score against Real Madrid and Barca. He is the first Spaniard to do so.
It was a result that owed a lot to a moment of guile from Ramires but more to a display of guts from the Brazilian and his team-mates after Terry’s needless dismissal for driving a knee into the back of Alexis Sanchez off the ball.
The Blues challenge was already rocking at that point with Terry’s centre-back partner Gary Cahill lost to injury and Barca having just levelled the tie through Busquets’ neat, close-range finish from Isaac Cuenca’s pull-back.
Within five minutes, the true cost of Terry’s indiscretion seemed clear as Iniesta collected from Messi in the box and swept the home side into the lead.
However, Chelsea have already shown during this Champions League campaign that they are made of stern stuff and somehow they raised themselves for a final salvo of the half, as Frank Lampard’s through-ball gave Ramires an opportunity he did not waste, chipping Valdes from 15 yards.
The goal was even more remarkable for the fact that the Brazilian had moments earlier had his dreams of a final appearance snatched away from him by a booking.
Chelsea’s joy looked likely to be short-lived, however. The second half had barely begun when Barca were given the chance to take hold of the tie again, Didier Drogba tripping Cesc Fabregas in the box.
Messi has scored 14 goals in the Champions League this season – one more would have given him the record for a single campaign – but he struck his spot-kick against the bar.
It was a let-off for Chelsea, but one they seized upon and their rearguard action in the remainder of the second half was stunning.
Barca had their chances, Cuenca seeing an effort saved by Cech and Messi striking a post from 22 yards, but the Blues deserved their luck.
In stoppage time, substitute Torres ran clear and rounded Valdes before slotting in to set up a showdown with either former boss Jose Mourinho’s Real Madrid or the side whose ground hosts the final, Bayern Munich.
The only sour note for the London side is that suspensions means they will have to do without Ramires, Terry, Branislav Ivanovic and Raul Meireles in Munich.
Source: BBC SPORT.