2140 GMT: SCORE UPDATE: FULL-TIME - Juventus 0 Bayern Munich 2 (0-4 on aggregate)
PSG defender Christophe Jallet (L) is beaten to the byline by Barcelona forward Pedro Rodriguez during the Champions League quarter-final second leg football at Camp Nou stadium in Barcelona on April 10, 2013. The sides drew the first leg 2-2 in Paris.
BAYERN MUNICH QUALIFY FOR THE CHAMPIONS LEAGUE SEMI-FINALS
90+4 mins: FULL-TIME - Barcelona 1 PSG 1 (3-3 on aggregate)
BARCELONA QUALIFY FOR THE CHAMPIONS LEAGUE SEMI-FINALS ON AWAY GOALS
90 mins: SCORE UPDATE: Juventus 0 Bayern Munich 2 (0-4 on aggregate)
Claudio Pizarro for Bayern rubs salt in Juventus wounds in Turin.
90 mins: PSG getting desperate here and just hoofing it long - seconds ticking away here and the impatient whistles are raining down from the stands.
86 mins: YELLOW CARD! Thiago Silva scythes down Lionel Messi near the halfway line and is rightly cautioned.
84 mins: SUBSTITUTION: Alex Song replaces David Villa for Barcelona.
83 mins: SUBSTITUTION: And another change for the visitors - David Beckham on for Marco Verratti
80 mins: SUBSTITUTION: PSG make a change - Ezequiel Lavezzi replaced by Kevin Gameiro up front
79 mins: YELLOW CARD! Ezequiel Lavezzi in the book for catching Marc Bartra on the ankle.
75 mins: The onus is squarely on the visitors now - and Ibrahimovic almost fashions an opening with a through ball to Lavezzi but he's just offside.
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70 mins: GOAL! Barcelona 1 PSG 1 (3-3 on aggregate)
Pedro Rodriguez levels it for Barca!
Messi goes on a mazy dribble befoe beating two PSG players and an injection of pace takes him towards the area -- he passes to David Villa who lays it off to Pedro who fires home an unstoppable shot with his left foot.
Barcelona are back in the driving seat and PSG must score again to go through.
65 mins: SCORE UPDATE - Juventus 0 Bayern Munich 1 (0-3 on aggregate)
Mario Manzukic has scored for Bayern in Turin and seemingly ensured the German side's place in the semi-finals.
64 mins: CHANCE - Andres Iniesta plays a quick one-two with David Villa inside the area before firing in a curling shot which forces Salvatore Sirigu into a smart save -- the sense of nervous expectancy at Messi's introduction is palpable.
61 mins: SUBSTITUTIONS - Vilanova makes the inevitable changes, bringing Lionel Messi on for Cesc Fabregas and the stadium erupts with applause.
He also replaces the hobbling Adriano with Marc Bartra.
54 mins: David Villa fires in a cross-shot which deflects behind off defender Alex's knee but the referee must have missed that as he awards a goal-kick -- it's fair to say the Barcelona players ar spitting feathers at that decision.
Messi is warming up on the touchline now, though rather gingerly, as is David Beckham for PSG - how long before a change?
50 mins: GOAL! Barcelona 0 PSG 1 (2-3 on aggregate)
Advantage PSG - Zlatan Ibrahimovic breaks the offside trap with a superb defence-splitting pass to Argentine midfielder Javier Pastore who bears down on Barcelona's goal and firing the ball over the onrushing Victor Valdes.
After that first half you have to say the visitors deserve it - surely Vilanova will now have to risk Messi?
1946 GMT: KICK-OFF - Barcelona get second half under way: can PSG score to force Tito Vilanova's hand with Messi?
1939 GMT: SCORE UPDATE - HALF-TIME IN TURIN: Juventus 0 Bayern Munich 0 (0-2 on aggregate)
1938 GMT: "Focus on poor Barca performance will be no Messi, but no one hitting normal standard," writes AFP sports correspondent Kieran Canning from the Camp Nou after that first half.
45+2 mins: HALF-TIME: Barcelona 0 PSG 0 (2-2 on aggregate)
45 mins: Xavi finds his Spain team-mate Iniesta on the left-hand side of the area 0 the midfielder beats Maxwell with ease before whipping in a cross to the far post but it's too high for Gerard Pique.
42 mins: YELLOW CARD! Barca full-back Adriano flies into a challenge on Lucas Moura and badly mistimes it.
The Brazilian's pace on the right flank has been a big plus for PSG so far.
40 mins: Iniesta finds Cesc Fabregas in plenty of space 30 yards out but the former Arsenal man is leaning back as he fires a disappointing effort over the crossbar.
31 mins: Barcelona striker David Villa shows Christophe Jallet a clean pair of heels to get to the byline on the left before chipping in a cross which Salvatore Sirigu does well to pat clear.
28 mins: CHANCE - Zlatan Ibrahimovic breaks clear on the left and chips in an inviting cross to the back post -- Lucas Moura climbs above Jordi Alba to fire in a header that Valdes has to palm over the crossbar.
Valdes then saves from Alex's header from the subsequent corner.
PSG building some real momentum here.
25 mins: CHANCE - PSG's Argentine striker Ezequiel Lavezzi played through in space on the edge of the area and strikes a low shot that Valdes does well to get a boot to.
This game is being played at a furious pace, both sides committing men forward in numbers.
21 mins: CHANCE - Pedro beats PSG's Christophe Jallet down the left side of the area and fires in a low cross that Sirigu does well to get a firm hand, though he palms it back to the Spanish winger who then shoots into the side-netting.
18 mins: CHANCE - Swedish striker Zlatan Ibrahimovic finds Lucas Moura in space near the edge of the area and the Brazilian midfielder unleashes a piledriver but it flies over Valdes's crossbar.
Some encouraging early signs for Carlo Ancelotti's side.
15 mins: Iniesta causing havoc in the PSG area with a series of deft touches around the French club's defenders, pulling off at least two nutmegs.
You can almost see his toes twinkling in the floodlights.
12 mins: Audacious attempt from Andres Iniesta -- the Spain midfielder spots Salvatore Sirigu off his goal-line and strikes a sweetly-hit shot that has the PSG 'keeper back-pedalling but the ball passes just over the crossbar.
7 mins: PENALTY CLAIM - Cesc Fabregas appeals for a penalty as he goes down after firing a right-footed shot from just inside the area but TV replays suggest there was little contact.
4 mins: CHANCE - PSG fashion their first opportunity as Argentine striker Ezequiel Lavezzi races clear down the middle but Gerard Pique manages to get back to toe the ball to Victor Valdes in the Barca goal.
Lavezzi hit the post after five minutes of the first leg last week and is already looking sharp tonight.
2 mins: CHANCE - Early free-kick for Barcelona 25-yards out which Xavi curls inches wide of Salvatore Sirigu's rigthand post. The PSG goalkeeper was at full stretch there.
1845 GMT: KICK-OFF - PSG get the game under way at the Camp Nou -- there's an electric atmosphere for this one...
1840 GMT: "Messi very quick out of the tunnel for warm-up, stretching & running a lot more than normal... almost as if he's trying to prove a point," writes AFP's @KieranCanning from the Camp Nou.
Meanwhile this from Tom Williams, AFP's London sports correspondent via his Twitter handle @tomwfootball:
"Another bold PSG team selection from Carlo Ancelotti - two holding midfielders, three very attacking midfielders/forwards, and Zlatan."
1833 GMT: "Camp Nou looking grand in the evening sunshine. PSG fans in good voice, atmosphere building nicely," writes AFP's Kieran Canning, at the Nou Camp covering tonight's game.
1827 GMT: More on Juventus v Bayern in Turin -- a combination of injuries and suspensions has forced Juventus coach Antonio Conte to make several changes for their quarter-final second-leg.
Juve are on the ropes after a 2-0 first leg defeat in Munich and the Bianconeri will be without striker Sebastian Giovinco tonight after a recent knee injury, meaning Fabio Quagliarella will partner Mirko Vucinic in Conte's preferred 3-5-2 formation.
With both Arturo Vidal and Stephan Lichsteiner suspended for one match each after last week's clash, Conte has also made changes to the midfield.
Frenchman Paul Pogba steps in to replace Chilean international Vidal and will partner Claudio Marchisio in the middle of the park with veteran Andrea Pirlo playing just behind.
Swiss international Lichsteiner's place on the right wing will be taken by Simone Padoin, while Ghanaian Kwadwo Asamoah keeps his usual place on the left flank.
1820 GMT: Here are the starting line-ups for tonight's other quarter-final second leg between Juventus and Bayern Munich in Turin:
Juventus (ITA)
Gianluigi Buffon (capt): Andrea Barzagli, Leonardo Bonucci, Giorgio Chiellini, Simone Padoin, Paul Pogba, Andrea Pirlo, Claudio Marchisio, Kwadwo Asamoah, Mirko Vucinic, Fabio Quagliarella
Manager: Antonio Conte
Bayern Munich (GER)
Manuel Neuer; Philipp Lahm (capt), Dante, Daniel Van Buyten, David Alaba, Bastian Schweinsteiger, Javi Martinez, Arjen Robben, Thomas Mueller, Franck Ribery; Mario Mandzukic
Manager: Jupp Heynckes
Referee: Carlos Velasco (ESP)
Kick-off in both games is 25 minutes away at 1845 GMT.
1818 GMT: "Actually think PSG look significantly stronger this week with Veratti and Motta in midfield ahead of Beckham & Matuidi," writes AFP's Madrid sports correspondent Kieran Canning from the Camp Nou.
Follow him for updates throughout the game via his Twitter handle @KieranCanning.
1813 GMT: Here are the full starting line-ups:
Barcelona (4-3-3):
Victor Valdes; Daniel Alves, Gerard Pique, Adriano, Jordi Alba; Sergio Busquets, Xavi Hernandez, Andres Iniesta; Pedro Rodriguez, Cesc Fabregas, David Villa
Coach: Tito Vilanova (ESP)
Paris Saint-Germain (4-2-2-2):
Salvatore Sirigu; Christophe Jallet, Thiago Silva, Alex, Maxwell; Marco Verratti, Thiago Motta; Lucas, Javier Pastore; Zlatan Ibrahimovic, Ezequiel Lavezzi
Referee: Bjorn Kuipers (NED)
1812 GMT: Lionel Messi has been passed fit to play in tonight's game -- but he's been left on the bench.
The World Player of the Year suffered a hamstring injury in last week's first leg in the French capital, which ended in a 2-2 draw.
In his absence, Cesc Fabregas and Pedro Rodriguez start alongside David Villa in attack, while Adriano lines up in central defence with both Carles Puyol and Javier Mascherano sidelined.
PSG coach Carlo Ancelotti has also left veteran English midfielder David Beckham on the bench despite being without the suspended Blaise Matuidi.
Marco Verratti and former Barcelona man Thiago Motta start in midfield for the visitors, with the rest of their team unchanged from last week's first leg.
WELCOME TO AFP'S LIVE REPORT on the second leg of the Champions League quarter-final between and Barcelona and Paris Saint-Germain at the Camp Nou, with the sides locked at 2-2 from last week's first leg.
Lionel Messi trained with Barcelona earlier this afternoon but the Argentina striker is waiting to hear whether he will be given the green light for the game tonight.
The World Player of the year is doubtful for the tie after suffering a hamstring injury in the first leg in Paris last week.
"Messi, Pedro and Adriano , all without the medical green light, trained on the Camp Nou pitch," a club statement said.
Barcelona's assistant manager Jordi Roura has said a decision on Messi's participation will be made at the last minute.
In tonight's other game Bayern travel to Juventus with a 2-0 lead from the first leg -- they will be looking to become the second German side into the semi-finals after Borussia Dortmund's dramatic late progress in their game against Malaga last night.
Kick-off in both games is less than an hour away at 1845 GMT (1945 BST) so stay with us for all the action as it unfolds in Barcelona and for goal updates from the Juventus Stadium in Turin.