Paris St Germain players celebrate after the Champions League win over Barcelona at the Olympic Stadium, Barcelona
Barcelona started well and their pressure paid off in the 19th minute when Marcus Rashford delivered a precise pass across the box to Ferran Torres, who slid in to beat the offside trap and slot past PSG goalkeeper Lucas Chevalier.
PSG, however, responded tenaciously despite missing captain Marquinhos and their starting attacking trio of Ousmane Dembele, Khvicha Kvaratskhelia and Desire Doue.
They took control of proceedings and equalised in the 38th minute when Nuno Mendes embarked on a dazzling run down the left, beating three defenders before setting up 19-year-old Senny Mayulu, who finished clinically into the bottom corner.
After substitute Lee Kang-in hit the post with a shot from the edge of the box in the 83rd minute, they finally scored a deserved winner from a quick counter in the 90th, with Achraf Hakimi crossing for substitute Goncalo Ramos to fire home from close range.
Meanwhile, Napoli striker Rasmus Hojlund netted twice either side of a Luis Suarez penalty to secure a 2-1 home win over Sporting on Wednesday and kick-start the hosts’ Champions League campaign with their first points of the competition.
After an uneventful opening at the Stadio Diego Armando Maradona, Napoli went in front in the 36th minute with a clinical counter-attack created by Kevin De Bruyne and finished off by Hojlund.
Sporting levelled from a Luis Suarez 62nd minute penalty but De Bruyne and Hojlund combined again for Napoli's winner 11 minutes from time, with home keeper Vanja Milinkovic-Savic making a late reflex save to deny the visitors.
Both sides now have three points, after Napoli lost their opening game 2-0 at Manchester City while the Portuguese club began with a 4-1 win over Kairat Almaty.
Borussia Dortmund were on the brink of blowing a two-goal lead for the second consecutive Champions League game before holding their nerve to earn a 4-1 victory over visitors Athletic Bilbao.
Undefeated across all competitions so far this season, Dortmund, second in the Bundesliga, looked to have learned their lesson after spectacularly conceding two goals deep in second-half stoppage time to settle for a 4-4 draw against Juventus on the first matchday.
On Wednesday they went 2-0 up with goals from Daniel Svensson and Carney Chukwuemeka in each half and with little resistance from the visitors, who were missing injured forward Nico Williams.
The hosts, who have kept a clean sheet in their last four Bundesliga matches, were disciplined at the back, keeping Bilbao well away from Gregor Kobel's goal for much of the first half.
Niko Kovac's team turned on the turbo in the 28th with a quick passing move and with Karim Adeyemi outsprinting his markers before cutting back for Svensson to drill in at the far post. Chukwuemeka then threaded the ball in from a tight angle to double their lead five minutes after the restart.
The Spaniards, however, improved after the break and pulled a goal back through Gorka Guruzeta in the 61st minute before missing several chances to level in a nail-biting finale. They put the ball in the net again but the home fans breathed a collective sigh of relief when Robert Navarro was offside.
Navarro came close again before Dortmund striker Serhou Guirassy, back from injury, settled home fans’ nerves with a deflected effort eight minutes from the end to restore their two-goal cushion. Julian Brandt then added another in stoppage time to seal their first win in the competition this season.