The first chance of the game fell to PSG’s Mahamadou Sangare, who dragged his shot wide, before a Michal Rosiak free-kick hit the wall and allowed the away side to counter.
Oumar Camara went for goal but Nygaard did well to adjust and save with his right foot. Axel Tape-Kobrissa then made a powerful run forward and shot just wide of the bottom left corner.
We played through the PSG press impressively, calmly keeping the ball under pressure, and we got our just rewards.
Dan Casey let fly from 25 yards out, forcing a fine save from Bilal Laurendon, and a Rosiak corner was then recycled by Theo Julienne.
After the latter crossed the ball to the far post, Rosiak fed it back across goal and Harriman-Annous was on hand to head in for 1-0.
Tape-Kobrissa was unable to keep his shot down from the edge of the area and we then had to make an enforced change, Max Dowman coming on for the injured Osman Kamara.
The Youth League’s youngest ever goalscorer almost got his second in the competition this season when he curled just wide of the far post after cutting in from the right, having been found by Ayden Heaven.
Max Porter made one change at half-time, bringing Louie Copley on for Casey.
Harrison Dudziak had a sight of goal straight away at the start of the second half as he volleyed towards the bottom right corner, but Laurendon got down to parry it past the post.
An Elian Quesada-Thorn cross reached Max Dowman who smashed the ball towards goal on his right foot, but Laurendon pushed the strike over the bar as the heavens opened in Borehamwood.
Nygaard did his job well at the other end too, tipping a Sangare free-kick over the bar, before a Yanis Khafi corner was headed over by Makaya Ibrahima Diaby.
Our goalkeeper then rushed off of his line and narrowed the angle to deny Adam Ayari, who had been put through on goal by Sangare.
Adamant about keeping the clean sheet, Nygaard threw himself at a shot from Mathis Jangeal from close range before Thomas Cordier fired wide from distance.
We made a double change with is minutes to go as Harriman-Annous and Julienne made way for Romari Forde and William Lannin-Sweet.
Sangare shot into the side netting as PSG hunted a late equaliser, but we held firm defensively to cap off an impressive performance.
LINE-UPS
Arsenal XI: Martin Nygaard, Julienne (Lannin-Sweet 84), Clarke, Heaven, Quesada-Thorn, Casey (Copley 46), Rosiak, Dudziak, Ferdinand, Harriman-Annous (Forde 84), Kamara (Dowman 32).
Substitutes not used: Ranson, Onyekachukwu, Ismail, O’Neill.
PSG XI: Laurendon, Diyinu Nzinga, Tape-Kobrissa (Slama 86), Diandaga, Cordier, Abo El Nay (Khafi 68), Diaby, Fanne Drame (Jangeal 79), Ly, Sangare, Camara (Ayari 68).
Substitutes not used: James, Lavenette, Mounguengue, Mbemba Nlandu.