The Gunners were 1-0 up when Maitland-Niles ran on to a loose ball and looked to pass back to Bernd Leno in the Arsenal goal.
But the defender had not realised that the German goalkeeper was approaching him, and managed to pass the ball into his own net despite Sokratis’ attempts to prevent it crossing the line.
Pierre-Emerick Aubameyang had earlier opened the scoring for Arsenal in the Joan Gamper Trophy, with Barcelona going on to win the game 2-1 thanks to Luis Suarez’s stoppage-time strike.
Maitland-Niles, naturally a midfielder or right-sided forward, was once again deployed at right-back and after his comical error, several disgruntled fans laid into the England youth international, claiming he’s not good enough for the role.
“Dont want to see maitland niles at rb ever again @UnaiEmery_,” said one.
Another tweeted: “Maitland just too casual too often.”
“I keep saying that boy Maitland Niles is a rubbish player,” reacted another.
One more fumed: “I’m sorry but Ainsley Maitland-Niles is simply stupid. He makes stupid mistakes every game because suffer of lack of concentration. He’s a donkey, but being english is saving him from criticisms. He is stupidly relaxed. He’s irritant. #GamperFest.”
One supporter harked back to another performance of the 21-year-old’s that he said was below par.
“Don’t forget, this same Maitland Niles costed us the Europa title against Chelsea. He was massively s**t that match,” they wrote.
Another declared: “I’ve never rated Maitland btw. I don’t think he’s gonna make it at Arsenal.”
And one other wrote: “Said it before and will say it again, Maitland-Niles is a disaster waiting to happen at right-back… too nonchalant and prone to silliness. @Arsenal #BARARS.”
Arsenal have chased Celtic left-back Kieran Tierney this summer but some members of the fan base declared a right-back should be a higher priority.
They insisted: “Arsenal need a right back more than we need a left back. Maitland is rubbish at defending to save his life.”
“Arsenal need a RB.. Can’t rely on AMN and Bellerin,” said one other.
“Never mind an new LB, badly need a RB, can’t look at AMN at RB any longer #Arsenal,” declared one more.