Arsenal were able to get the better of Chelsea in what was a close encounter at the Emirates.
An early goal from Morgan Rogers set Arsenal behind immediately, but following a disallowed goal from Calafiori, Havertz was able to score against his former club before half-time.
Arsenal captain Martin Odegaard was able to score the winner shortly after the break, finding himself in acres of space thanks to great movement from Kai Havertz.
Story of the Match
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Arsenal made one change going into this match, opting to use Ezri Konsa instead of Mosquera. Chelsea, on the other hand, has made several changes, with Reece James back in for Malo Gusto, and Josh Acheampong in for Levi Colwill.
Morgan Rogers opened up the scoring nearly immediately for Chelsea - after being heavily linked to the Gunners over the summer. Rogers was able to place the ball into the bottom corner with an astonishing volley from outside the box.
Havertz won a free kick for Arsenal following a light challenge from Wesley Fofana. Odegaard put a dangerous ball across the grass into the feet of Riccardo Calafiori, but the Italian was unable to make a connection, leading to a frenzy in the box.
Wesley Fofana stopped a promising Arsenal attack, putting out a ball from Ben White for a corner. Following the delivery of the corner Saka ran into to try and do something in the box but was called offside.
Jorrel Hato gave away another free kick after ten minutes in a game that was shaping up to be a bitter encounter. After a Declan Rice delivery, it was a scrummage in the box, leading to Calafiori putting the ball into the back of the net. Konsa, though, was deemed to have been in an offside position, which led to the goal being disallowed.
Joao Pedro got the first yellow card of the game and the first for him this season after just shy of 15 minutes.
Saka forced a save from Emi Martinez, finding space inside the box; a placed shot to the near post was parried away, though, by the Argentinian.
Arsenal dominated the ball for the following minutes, eagerly trying to get back into the game; Chelsea were able to weather the storm, though.
Cole Palmer got the first chance of the game for Chelsea since the goal, shooting from distance to force a save from David Raya.
Reece James took his own chance a minute later, shooting from distance himself. Raya was able to make the save.
Tzolis was able to make a break away and set the ball up for Kai Havertz, who chose to backheel it to Martin Odegaard, whose shot came to nothing.
Havertz levelled the game for Arsenal with a fantastic shot. The German found space for himself at the edge of the box and was able to place it in the bottom corner at the near post.
The Gunners continued to apply pressure to Chelsea; Lewis-Skelly pulled the trigger from distance, but the ball went over for a goal kick.
Pedro took a shot from just over the halfway line as he spotted Raya off his line, but the striker's shot was wide.
Arsenal began to resume their normal style of play in the final minutes of the first half, playing with more restraint and passing the ball between themselves.
Cole Palmer got a yellow card for taking down Kai Havertz as the German made a promising counter-attack.
The subsequent free kick was taken by Declan Rice, who laid it off for Saka.
A scuffle between Ben White and Lavia ensued following a crunching tackle from the Chelsea man; neither player was booked, though.
Pedro Neto was clean through following a counterattack; the winger was able to cut into the box and curl an effort, but it could only smash into the post.
It proved to be the final crucial action of the half.
There were no changes as the second half began, with Chelsea maintaining the ball in the minutes following the break.
Arsenal Captain Martin Odegaard put the red side of London ahead just before 50 minutes, following a pass into the box from Tzolis. A dummy from Havertz led to the Norwegian having acres of space in the box to deftly finish the chance.
The Gunners stayed in control of the ball following the goal, forcing the Blues into their own half.
Konsa won a cheer from the Arsenal fans as he delivered a firm sliding tackle on former teammate Morgan Rogers, preventing the goalscorer from being through on goal.
In a humorous incident, Tzolis was given a yellow card for demanding a booking for Lacroix following a crunching tackle; his demands were answered, though, as Lacroix was given a yellow.
Lavia and Hato came off for Pep Chavarria and Malo Gusto, with Lavia looking disappointed following a game well played by the midfielder.
Malo Gusto got his first action of the game shooting from outside the box - the ball went wide off the mark, however.
It was end-to-end action following the substitutions as Chelsea aimed to get back in the game. Forcing multiple saves from David Raya.
Arsenal matched with their own defensive substitutions, bringing on Hincapie for Calafiori and Zubimendi on for Myles Lewis-Skelly.
Zubimendi made an immediate impact off the bench as he nearly put Arsenal two to the good, but his shot was deflected.
Saka was able to get a first-time shot off in the box a minute later, but Martinez was able to parry it out for a corner as Arsenal piled on the pressure; a flick from the head of James led to another corner.
Arsenal won yet another corner; Saka took it cleanly into the box, but Martinez was able to claim it on the line.
Both sides went toe to toe with one another, as Chelsea looked desperate to equalise with only 15 minutes to go.
Pedro Neto was able to spin the ball into the box, but the only player able to meet it was David Raya, who claimed the ball.
The two goal scorers, Havertz and Odegaard, came off for Merino and Gyokeres, marking the Swede's first Premier League appearance this season.
Pedro was able to win a corner for the Blues with just ten minutes of normal time to go.
Malo Gusto took the set piece, but David Raya was able to get two hands on it.
Brazilian youngster Estevao came on for the closing stages in place of Pedro Neto.
Morgan Rogers was booked in the final minutes as the two sides scuffled in the closing stages of a bitter London derby.
Rogers soon came off to a boo from Arsenal fans as former Gunner Danny Welbeck came on to try and change the game in the final minutes.
David Raya saved the day for Arsenal in the final minutes as Estevão forced the keeper into a fingertip save as he curled an effort into the far corner.
Chelsea grew increasingly desperate in the final minutes to level the game but Arsenal's defence continued how they have performed for the last few season as an unbreakable wall.
A Chelsea free kick was the last chance of the match as Merino was shown a yellow.
Player of the Match: Kai Havertz
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It was Kai Havertz who scored the goal to level the game against his former side, and the German's exceptional movement allowed Odegaard to be in acres of space to score his winning goal.
Alongside his contributions to the goals, his overall play was exceptional, showing great perseverance following a rough start for the Gunners.