The goalkeeper joined from Bayer Leverkusen for a fee of £20million with a reputation for being comfortable with the ball at his feet, but he didnt look too assured at the Emirates on Wednesday night.
Many called for Leno to come into the starting XI after Cech nearly scored a calamitous own goal in Arsenals opening day defeat to Manchester City. But Unai Emery kept the faith with Cech and the former Chelsea man impressed against Everton at the weekend.
With Cech rested for the third-round tie with Brentford, though, Leno was again selected – and Arsenal fans were experiencing déjà vu shortly before Danny Welbecks first-half brace.
The German made an eerily similar mistake when in a game between Leverkusen and Augsburg back 2015.
Luckily for Arsenal, his error on Wednesday evening didnt end up in the back of the net as this one did.