Arsenal failed to cement top spot in their Europa League group, following a 2-1 home loss to German side Eintracht Frankfurt on Thursday night.
In a match that recorded one of the lowest fans' attendance at the stadium, it was the home team that took the lead in the first half, before the Daichi Kamada's brace in the second half made all the difference.
The Gunners opened the scoring in the first minutes of first-half added time to lead 1-0 going into the break, but the visitors scored 10 minutes after the break to pull level, before grabbing the winner.
Arsenal should have taken the lead on the 11th minute, but a big chance went begging with Aubameyang and Willock fighting for Saka's inch-perfect cross.
Arsenal fans then got a scare as David Luiz was injured in the 12th minute, and even though he played on after receiving treatment, he was eventually withdrawn and replaced by Mateo Guendouzi.
The home team kept knocking on Frankfurt's door from time to time, with Aubameyang coming close twice.
With 45 minutes gone and the match headed for a draw in the opening period, the skipper popped up to finish Martinelli's ball from the right flank, which was initially meant fo Saka.
Xhaka almost made it two before the break but slipped as he was about to take a shot with his ball going off-target.
Frankfurt pulled level ten minutes after the restart, Daichi Kamada beautifully finding the back of the net from just outside the box.
Kamada then turned the game on its head with his second of the night for Frankfurt, following a corner kick clearance that went as far as the Japanese.
He had all the time to make a first and second touch, before firing past Emi Martinez for the winning goal.
Arsenal pushed for the elusive equalizer which never came, as pressure mounted on manager Unai Emery.
The side is winless in their last seven matches in all competitions, with the few fans at the stadium expressing their feelings with 'Emery Out' banners.