At the final whistle of this absorbing game, Lionel Messi strolled around, shaking hands, receiving an embrace from Paris St-Germain's Ezequiel Lavezzi, almost oblivious to the emotions sweeping the terraces at his impact.
Half an hour earlier, Messi had risen from the bench, helped create Barcelona's equaliser and suddenly all the fears that had inhibited the hosts disappeared. Make no mistake: Messi rescued Barcelona last night.
He cannot have been fully fit, and he must have been wary of that newly healed hamstring, but he was there when his team needed him. Messi combined with David Villa to provide the chance for Pedro to cancel out Javier Pastore's opener. So tomorrow's draw involves Barcelona, Real Madrid, Bayern Munich and Borussia Dortmund.
Yet credit must be paid to PSG, who were superb, particularly Pastore, Lavezzi and Zlatan Ibrahimovic. Carlo Ancelotti's side played with precision, pace and intelligence, but Messi's class told in the end.
All eyes had been on the bench before kick-off. Messi had recovered from his hamstring strain but was kept in reserve for an hour, meaning Cesc Fabregas started but failed in the false No 9 role. Yet with PSG taking a deserved lead after 50 minutes, and Barcelona painfully lacking a cutting edge, Tito Vilanova had to send on Messi on the hour. A simple move, a crucial move.
Messi immediately gave Barcelona focus and confidence, helping them equalise. Barcelona really needed their magical No 10. PSG had been so good.
Their changes improved them. Ancelotti had demoted David Beckham to the bench, opting for the greater mobility of Marco Verratti and Thiago Motta with Blaise Matuidi suspended.
PSG were counter-attacking quickly, Pastore and Ibrahimovic combined to smuggle Lavezzi through. That moment came to nothing but it set the tone: PSG, who had to score, committed players forward.
They swiftly sensed that Barcelona were vulnerable through the middle. Adriano was no replacement for Javier Mascherano, let alone Carles Puyol.
Mistakes and PSG's speed on the counter brought serious discomfort to Barcelona fans, whose mood improved only when Messi arrived. Sergio Busquets lost the ball to Lavezzi, who ran through and only Gerard Pique's alertness stopped him. Errors scarred Barcelona's usually pristine work. Even Iniesta gave the ball away, the type of event surely followed by four horsemen saddling up.
Barcelona showed some of their elegance moving the ball into the final third but there was no finish in the first half. Pedro, Villa and Fabregas were poor.
There were moments of hope. Iniesta capped a long move with a shot blocked by Christophe Jallet. Villa concocted a neat flick to Dani Alves. Iniesta, spotting Salvatore Sirigu off his line, lifted the ball goalwards from 45 yards. The crowd followed its passage, all but a small quarter of the Nou Camp willing it to drop, but it cleared the bar.
PSG were content to hit on the counter. From a Jallet cutback, Lucas Moura's angled drive was saved by Valdes. Iniesta attempted to sharpen Barcelona's surges, dribbling past Jallet and Verratti. He then shimmied away from Ibrahimovic. But Barcelona were not hurting PSG.
The Nou Camp began whistling at one long PSG move. Well prepared by Ancelotti, the visitors kept looking to exploit rare hesitancy by Barcelona. Ibrahimovic worked the ball calmly through the middle to Lavezzi, whose quick break had taken him ahead of Jordi Alba. Valdes saved well and Pique swept up the pieces.
Below par with dead balls, Ibrahimovic's creativity from open play almost brought PSG reward. He stood up a cross that was met by Lucas, whose header was pushed away by Valdes. When Adriano then fouled Lucas, Ibrahimovic's free-kick slammed into the wall.
PSG were getting closer. Five minutes into the second half, they took the lead. Ibrahimovic's touch had been teeing up his team-mates all evening and he threaded a superb pass here, sweeping the ball through for Pastore. The Argentinian had timed his run perfectly, showing such composure in lifting the ball left-footed past Valdes.
Dismay spread through the tiers of Barcelona's support. Their mood lifted when they spotted Messi emerging to warm up. He came on for the disappointing Fabregas after 62 minutes, making an impact within nine.
Messi collected the ball just outside the area, advanced and flicked a delicate pass into the heart of PSG's defence for Villa, who helped it back to Pedro. His response was exceptional, the ball rifled past Sirigu.
With eight minutes remaining, Ancelotti sent on Beckham, who operated deep, slipping one good ball down the line to Jallet but then being totally caught out by Xavi's movement.
PSG had given so much. Lucas fouled Busquets. Thiago Silva fouled Messi.
PSG's defence was then exposed by a delicate turn from Iniesta, who eluded Jallet so elegantly but shot into the side-netting. PSG had a final chance but Valdes was equal to Ibrahimovic's header. Barcelona were through. (© Daily Telegraph, London)