Victor Moses opened the scoring for Chelsea but Sead Kolasinac equalised for Arsenal - both goals coming as a result of a set-piece. In the end, it was the Gunners who triumphed in the penalty shootout as Thibaut Courtois (?) and Alvaro Morata failed to find the back of the net.
And it's a pre-season treble yet again for Arsenal.
We've just seen Mertesacker's face again after his collision with Cahill's elbow. It looks like someone took a butcher knife to his eyebrow! That's one scar that won't fade anytime soon.
82' Arsenal capitalise on the free-kick and extra man. Xhaka's free-kick is floated in and Sead Kolasinac rises above the rest to head it home past Courtois who was rooted to the spot. 1-1!
80' RED CARD! Pedro attempts to stop Elneny in his tracks but ends up stepping on the back of his ankle. His boot was raised and Elneny is in pain. The referee goes into his pocket and pulls out a red card - straight red!
78' Morataaa... GOES HIGH! A hopeful cross into the box beats every Arsenal defender and Morata makes the run in from the right. He gets a foot to it form a narrow angle but it's way off target.
76' Xhakaaaaa... SAVE! Xhaka's shot from long-range was travelling! It looked destined for the top corner but Courtois makes a fine dive to his right to deny the Arsenal midfielder.
74' SUBSTITUTION: The moment Chelsea fans have been waiting for - Alvaro Morata comes on for Michy Batshuayi with less than 20 minutes to make an impression.
71' FOUL! Kolasinac again. The man is on a mission to destroy a fellow human being and this time Moses runs into a tree. A Bosnian tree running at him at 50mph.
68' FOUL! Kolasinac barges into Pedro from behind and although he protests his innocence, the referee thinks otherwise. Chelsea have a free-kick and Luiz is standing over it. He doesn't go for goal though - opting to lob it over the wall instead. Nothing comes of it.
66' SUBSTITUTION: Olivier Giroud and Theo Walcott come on for Alexandre Lacazette and Alex Iwobi. Walcott looks a lot like a certain Leicester City winger all of a sudden - like Theyad Wahrez.
65' So close, again! Iwobi almost manages to find Lacazette but a deflection allows Courtois to step up and make the clearance before the French striker can pounce.
63' David Luiz may have taken a knock to his head but he's as alert as ever. With Welbeck through on goal on the left side of the box, he makes a quick tackle to deny the striker a pass or shot on goal.
59' Arsenal hit back with two attempts on goal. The first was a cross from Bellerin that was just missed by Elneny making the near-post run. Elneny then gets another chance to put the ball in but it swerves dangerously goal-ward and Courtois makes a desperate save.
56' Another collision and TWO Chelsea players are down. David Luiz, Gary Cahill and Rob Holding go up for a header and the two Chelsea defenders clash heads. Holding somehow comes out unscathed.
The physios are on the pitch and the two centre-backs will take time to get back on their feet.
54' Kante attempts a cute back-heel that even takes Batshuayi by surprise - who eventually loses possession. A frustrated sigh can be heard from the end with Chelsea fans.
50' WIDE! An Arsenal counter sees the ball fall to Elneny outside the box and he tries to volley it into the top corner with his left foot, But it curls away from goal, much to Chelsea's relief.
47' That was quick! A Chelsea corner sees the ball initially cleared but headed back into the box by Cahill. While the rest of the Arsenal defence was stepping up, Victor Moses ran through and slotted the ball past a stranded Petr Cech. Moses was onside - no question about it.
It's been an interesting half. The Gunners got off the blocks quickly and dominated proceedings in the first 20 minutes. But Chelsea have had shots on target to put pressure on Cech.
If the scoreline remains the same after another 45 minutes, we could see the new ABBA penalty shootout. (No, not the Swedish pop group - the shootout format)
44' Wow, what was that?! Iwobi gets room to gallop and Chelsea's defence backpedal quickly to get back into the box. The Ox receives the ball and tries to set up Iwobi who dances around three Chelsea players before taking a shot on goal. But it's weak and Courtois makes the save.
41' How about that, Kolasinac drives through Chelsea's midfield with the ball and is let down by Oxlade-Chamberlain who did not catch up. Kolasinac's pass is barely kept in play by the Ox but his cross is without any purpose and Kolasinac doesn't look too pleased.
37' PENAL... NO, WAIT. DIVE! It's a dive from Willian! At first glance it looked like Bellerin clipped him in the box but replays showed Willian tripped, clipping his own leg and going down. The protests certainly didn't help and he is booked!
35' SAVE! Pedro runs into the Arsenal box with the ball and fires a shot on goal to Cech's near post but it stings his gloves. That shot was on target.
