Trailing by two goals from the first leg in France, Unai Emerys side overturned the deficit with a 3-0 victory that puts them through to the quarter-finals of the tournament. Maitland-Niles was particularly impressive throughout and even grabbed his first ever goal at the Emirates.
It was a stellar showing from the full-back, who is also adept at playing in midfield and on the wing. His headed finish was just his second goal for the club and was a fitting way to cap a hugely promising display.
After the match Hartson told BT Sport viewers, via Football.London, that the youngster was very impressive, adding: "He defended really strongly. He gets strong there, makes sure he pushes that out. That one there is physical, quick to react.
"Tracking. Concentration levels excellent. That one there, he’s pointing where he feels the ball should go. And I believe he’s as good going forward."
The Arsenal academy product came in for significant praise from fans and players alike, with many suggesting that he is ready for a more prominent role under Emery.
Timely reminder that Ainsley Maitland-Niles is a baller.
— Aleksi (@Skrufkin) March 14, 2019
Whether he does, indeed, receive more game time in the Premier League and European competition may depend upon what system the Spaniard chooses for his side. Hartson clearly appears to think as much, stating: "It’s easier when you play with a three at the back, as a wing-back, to get forward than, for instance, when you play a four.
"He was so calm there with that first goal, sliding that ball into Aaron Ramsey," he added.
"His positional sense is magnificent."