Chelsea’s goalkeeper, Thibaut Courtois and new £70 million striker, Alvaro Morata, missed the target from 12 yards as Arsenal collected the season’s first piece of silverware.
Arsenal came from behind to draw 1-1 and win the penalty shootout that followed by four goals to one.
Chelsea had led early in the second half, with Victor Moses ghosting in to score, after a corner in the 46th minute. But when the Spaniard, Pedro, was sent off for a lunge at Mohamed Elneny with eight minutes left, the whole picture changed.
From the resulting free-kick, Arsenal’s new Bosnian defender, Sead Kolasinac, headed Arsene Wenger’s team level and that brought the game to a shootout.
And it was a shoutout that was as unusual as it was dramatic, with the new ABBA system dictating that the teams no longer take alternate kicks.
Captain Gary Cahill scored his team’s first but after Theo Walcott and Nacho Monreal then scored back-to-back kicks for Arsenal, Courtois blasted his shot over and then Morata dragged his embarrassingly wide.
This left Alex Oxlade-Chamberlain and Olivier Giroud to convert successive penalties for Arsenal and settle matters.