Birthday boy Andreas Christensen fired the winner shortly after coming on, and Raphinha hit a brace as Barcelona claimed a thrilling 3-2 comeback victory at Paris Saint-Germain on Wednesday in the Champions League quarter-finals.
Raphinha opened the scoring in the 37th minute against a shaky PSG defence, and made it 2-2 in the 62nd with a delicate effort, before Christensen headed the 3-2 winner in 77th with his first touch on the day he turned 28.
PSG had fought back after the restart as Ousmane Dembele netted a 48th-minute equalizer against his former club, and Vitinha put the hosts 2-1 up in the 51st.
Barca play the second leg at home and will like their chances to get a first semi-final berth since 2019, while PSG's bid to win finally win the elite event may end prematurely again.
"It was hard work, there's still a game to go and Paris remain one of the best in Europe right now. We are only at the halfway stage after this, it's a small advantage but it's a big victory," Barca coach Xavi Hernandez said.
PSG coach Luis Enrique, in charge at Barca when they famously routed PSG 6-1 in 2017, told TNT Sport: We created some chances but for us it's a pity. There's still the spirit to go to Barcelona and try to win."
If Barca prevail they could face an all-Spanish semi-final after Atletico Madrid beat Borussia Dortmund 2-1 in the day's other game.
Atletico made the most of Dortmund defensive mistakes to score from Rodrigo de Paul in the fourth minute and Samuel Lino in the 32nd.
But substitute Sebastian Haller kept the Germans in the tie by netting in the 82nd minute.
"There were moments when we could have scored a third but the truth is that we have suffered a lot in the second half. Now we need to go there and hopefully we can win," Atletico forward Antoine Griezmann said.
All ties are well balanced as on Tuesday record winners Real Madrid and title holders Manchester City played to a thrilling 3-3 draw, and there was also no winner in Arsenal's 2-2 against Bayern Munich.
The matches took place amid beefed up security after an Islamic State terror threat via a media outlet linked to the group.
PSG dominated early but a long kick from Barca goalkeeper Marc-Andre ter Stegen to release Raphinha was a sign of what was to come, with the Barca forward stopped by keeper Gianluigi Donnarumma who had rushed out of his penalty area.
Barca 16-year-old Lamine Yamal, the youngest ever player in a Champions league quarter-final alongside 17-year-old team-mate Pau Cubarsi, almost got his first goal in the elite event but his looping header was cleared off the goal-line by defender Nuno Mendes.
The visitors eventually got the breakthrough when Robert Lewandowski's shot was punched by Donnarumma to Raphina who calmly smashed home.
However, PSG turned matters around right after the restart.
Dembele smashed the equalizer into the roof of the net after Barca failed to clear, and Vitinha's low shot into the far left corner made it 2-1 three minutes later.
PSG pressed for the third but key substitutions by Xavi swung the pendulum back in their favour.
Pedri, who had come the previous minute, chipped the ball over the top for Raphinha to volley the 2-2 equalizer.
Dembele was denied by the right post but Barca had more stability since the introduction of Pedri and Joao Felix, and Christensen then also came on in the 76th and swiftly headed home Ilkay Gündogan's corner kick for the winner.
"To come here and to return home with a win is pretty positive I'd say. Winning is important, but this tie is nowhere near finished," Raphinha said.
Atletico had the perfect start when they were gifted an early by Dortmund. Goalkeeper Gregor Kobel played a risky pass through the centre to Ian Maatsen, who lost the ball to De Paul which allowed the Argentinian to score from inside the penalty area.
The second came after another Dortmund mistake. Mats Hummels and Nico Schlotterbeck were in each other's way after a throw-in, the ball came Griezmann who chipped over to Lino to hit home, a few minutes after Lino had been booked which means he is suspended for the return leg.
Dortmund woke up for the second half and it was substitutes here as well who made the difference to keep alive their hopes of a first semi-final berth since 2013.
Haller drilled the ball into the bottom left corner off Brandt for 2-1, and Dortmund almost levelled on virtually the last play of the game when Brandt's header hit the crossbar.
"If we play like we did in the second half today in the second leg, then it can definitely turn into something very good next week," Dortmund captain Emre Can said.
