Reigning champions Arsenal came from behind to beat big-spending Chelsea in a pulsating London derby at Emirates Stadium.

Chelsea stunned the home fans by taking a second-minute lead through £117m summer signing Morgan Rogers' volley after the Gunners failed to clear Reece James' free-kick.

That was the first goal Mikel Arteta's side have conceded this season.

Despite their flying start, Chelsea had not kept a clean sheet in their previous 18 Premier League games and Xabi Alonso's side were forced to withstand wave after wave of Arsenal pressure.

Emiliano Martinez denied Bukayo Saka, while Jorrel Hato and Wesley Fofana each made crucial blocks before the Gunners levelled in the 25th-minute after former Chelsea forward Kai Havertz beat Martinez at his near post with a well-placed finish.

In a high-quality match, Chelsea - who spent close to £350m in the summer transfer window - came within a whisker of retaking the lead.

After captain James had forced David Raya into a save from outside the box, Pedro Neto hit the post after a wonderful solo run before Martin Odegaard settled it in the 50th minute.

The Arsenal captain beat Martinez after Havertz's clever dummy, the Norwegian's second goal in three Premier League games.

Chelsea substitute Estevao thought he had equalised right at the end of the game but Raya produced a brilliant finger-tip save as the Blues lost for the fifth straight league game at Emirates Stadium.

This was Arsenal's first major test against rivals who had also won their opening two matches, and they passed it after exposing Chelsea's defensive vulnerabilities.

Along with Manchester City, the Gunners are one of only two teams to have a 100% winning record after three games - but their latest success came after an unexpected setback.

Arsenal's first league title for 22 years was built on their stubborn defence and there will be questions about how they conceded so early against their London rivals.

Yet the spirit and character that propelled them towards the Premier League crown last season remains strong after they were made to dig deep before celebrating an eighth straight Premier League win stretching back to last season.

Arsenal's failure to bring in an elite forward during the transfer window has led to questions, yet it was two familiar faces whose goals turned it around for Arteta's side in the shape of Havertz and Odegaard.

Meanwhile, it was a solid first start in red and white for Ezri Konsa, whose £55m arrival from Aston Villa has gone under the radar, as Arsenal signed off with three points before the start of their Champions League campaign away to Napoli on Wednesday.

Chelsea finished in 10th place, a whopping 33 points behind Arsenal last season.

While Alonso's side still have plenty of catching up to do, there was evidence in this game they will compete towards the top end of the table this time.

Alonso, however, needs to get on top of his side's defensive frailties.

While Chelsea have goals in them this season in the shape of Rogers - who has scored two and provided one assist in his first three league appearances for his new club - Joao Pedro and Cole Palmer, they also have holes at the back.

Chelsea have not kept a clean sheet in the league since 17 January and although they pushed Arsenal all the way, there will be disappointment about both goals they conceded.

Argentina World Cup keeper Martinez will feel he should have done better with Havertz's equaliser, while Chelsea's defence was found wanting for Odegaard's winner.