Nigerian striker George Ilenikhena scored on his Champions League debut as Monaco produced an upset against 10-man Barcelona.
The 18-year-old substitute raced on to Vanderson’s long ball over the top of the defence in the 71st minute and blasted his shot past Marc-Andre ter Stegen.
Eric Garcia had earlier been shown a straight red card with just 10 minutes gone when he fouled Takumi Minamino as the last man after a poor pass out from the back by Ter Stegen.
Monaco took the lead soon after when Maghnes Akliouche slotted past Ter Stegen who was rooted to the spot.
Barcelona’s own teenage star Lamine Yamal equalised with his first Champions League goal when he latched on to a long ball and cut inside before drilling a low shot into the bottom corner.
But Ilenikhena’s goal, his first since signing from Royal Antwerp in the summer, condemned Barcelona to an opening defeat.
Vanderson’s strike from the edge of the area was pushed past the post while Minamino had an effort deflected on to the crossbar for the hosts.
It could have been a more emphatic win but Folarin Balogun had a penalty overturned late on following a video assistant referee (VAR) check after he was adjudged to have gone down too easily under the challenge of Inigo Martinez.
