Victor Moses fired Chelsea into the lead early in the second-half but Arsenal hit back through Sead Kolašinac to force the game into penalties after Pedro was sent off for a reckless foul on Mohamed Elneny.
In the shoot-out, Thibaut Courtois and Álvaro Morata both missed spectacularly for Chelsea which opened the door for Giroud to slam home the decisive kick and give Arsenal the season’s first piece of silverware.
Here are five things we learned from the game.
Lacazette looks like a star in the making
Arsenal fans would be foolish to draw comparisons between Alexandre Lacazette and Thierry Henry. They’re very different players. The good news, though, from a Gunners perspective is that Lacazette looks like he can be the sharp, dynamic attacking force the club has missed since the departure of their all-time top-scorer.
The 26-year-old was eye-catching against Chelsea. A willing and intelligent runner, Lacazette moved Chelsea’s defenders and that created space for Danny Welbeck and Alex Iwobi.
He came close, too, striking the woodwork with a curling effort, denied a dream debut goal by mere inches.
Another encouraging sign was that Lacazette combined smoothly at times with Welbeck and Iwobi. With all due respect to those two players, replace them with Alexis Sánchez and Mesut Özil and Arsenal’s attack is shaping up to be devastating.
Letting Matić go to United may come back to haunt Conte
Chelsea fans will undoubtedly laugh it off, but Nemanja Matić leaves for Manchester United and suddenly an ocean of space appears in the Blues’ midfield.
Matić is divisive. Some view him as a glorious, towering presence who dominates the middle of the park. While some regard him as more of an immobile, lumbering liability, devoid of creativity and easy to get past.
While both arguments have degrees of validity, Matić offers extensive Premier League experience while, at his best, he formed a fearsome partnership with N’Golo Kanté.
The sight of Arsenal pouring forward into large patches of unoccupied green space would have been a worrying sight for Conte. Although the Italian still has the services of Tiémoué Bakayoko to enlist, it remains to be seen whether their new enforcer is hit or miss. Keeping Matić in reserve would have been a shrewd move.
Whatever you look at it, Chelsea have risked strengthening a bitter rival while losing a perfectly good squad player, assuming that Kanté and Bakayoko will start.
Good omens for ever-improving Elneny and Xhaka
Not so long ago the jury was still out on Mohamed Elneny, and not so long ago the jury had returned a guilty verdict on Granit Xhaka.
How things change. The former enjoyed one of his finer afternoons in an Arsenal shirt while the latter was a picture of poise and panache, laughing at the 2016 Xhaka as he masterfully patrolled the Wembley turf.
Elneny was ultra-composed, completing 94% of his passes and attacks moving forward with fluidity and purpose.
Xhaka, in stark contrast to the ill-disciplined wrecking ball who arrived from Borussia Mönchengladbach last summer, bossed the midfield.
A fantastic lofted pass set Danny Welbeck up for an early chance, while his own long-ranged missile required a brilliant save from Courtois to stop it from flying into the top-corner.
Determined to deliver, though, Xhaka’s pinpoint cross allowed Kolašinac to head home the equaliser. Deservedly, Xhaka was named Man of the Match, but Elneny deserves plaudits too and today bodes extremely well for their prospective future partnership.
Do Chelsea need to sign another striker?
Forgetting for a moment that Morata missed a presentable opportunity with his head and skewed a penalty wide in the first 15 minutes of his Chelsea career, with only him and Michy Batshuayi, Conte’s options up front are looking a bit threadbare.
Considering the Blues are expected to retain the Premier League title and at least progress to the latter stages of the Champions League, two strikers may not be enough for them to deliver on all fronts after not having to negotiate European football last season.
Diego Costa’s absence from the matchday squad against Arsenal all but confirms his departure is imminent. While Morata is undoubtedly talented, it’s difficult to replace a player as instrumental as the tempestuous Spaniard who is an Atlético Madrid transfer target.
Batshuayi started against Arsenal but still looks far from the finished product, so Conte may need to dip back into the transfer market to ensure Chelsea don’t suffer from post-Costa striking woes this season.
Sead Kolašinac may prevent a headache for Wenger
Looking beyond his goal – which, it must be said, was taken with aplomb – there were plenty of positives to be drawn from Kolašinac’s Arsenal debut.
Being thrown into the heat of battle following an injury to Per Mertesacker, Kolašinac looked a natural fit as the left-sided member of a defensive trio, but he can also fulfil the role of left wing-back naturally.
The brawny Bosnian brought fans to the edge of their seats too when he galloped forward with the ball, doing enough to stake an early claim for a starting berth in Wenger’s first-team.
Kolašinac completed 93% of his passes, won one aerial duel and, of course, scored the equaliser, rising to guide Xhaka’s cross into the far corner.
In an era of preposterous transfer fees, Kolašinac’s arrival on a free transfer from Schalke may prove to be one of the bargains of the season.