Chelsea beat Arsenal 3-2 in London derby thriller

Soccer Football - Premier League - Chelsea v Arsenal - Stamford Bridge, London, Britain - August 18, 2018 Chelsea's Pedro celebrates scoring their first goal Action Images via Reuters/John Sibley

(Reuters) - CHELSEA 3 ARSENAL 2

Chelsea beat Arsenal 3-2 in a pulsating London Premier League derby on Saturday with defender Marcos Alonso scoring an 81st-minute winner after the Gunners had fought back from an early 2-0 deficit.

Soccer Football - Premier League - Chelsea v Arsenal - Stamford Bridge, London, Britain - August 18, 2018 Chelsea's Cesar Azpilicueta in action with Arsenal's Alex Iwobi REUTERS/Toby Melville

Chelsea have now won both games under new manager Maurizio Sarri while Arsenal have suffered back-to-back defeats under Arsene Wenger's successor, Unai Emery.

But any result would have been possible in a see-saw game marked by poor defending and astonishing misses, with Arsenal particularly guilty of both in the first half.

Sarri admitted his side suffered a "horrible" 15 minutes which could have cost them dear.

Soccer Football - Premier League - Chelsea v Arsenal - Stamford Bridge, London, Britain - August 18, 2018 Chelsea's Pedro celebrates scoring their first goal with Alvaro Morata and Marcos Alonso Action Images via Reuters/John Sibley

"Three points is an important target for us, we did very well for 75 minutes but inside that, 15 minutes were horrible," he said.

Chelsea went ahead in the ninth minute when Pedro buried a cross by Alonso. Out-of-form striker Alvaro Morata scored only his second league goal of 2018, fed by a through ball from Cesar Azpilicueta 11 minutes later.

Arsenal clawed their way back into the game in the 37th minute when Henrikh Mkhitaryan drilled in a low shot that Kepa Arrizabalaga -- the world's most expensive goalkeeper making his home debut -- will have been disappointed to have let in. Alex Iwobi made it 2-2 four minutes later as Arsenal exploited Chelsea's vulnerability on the flanks.

Soccer Football - Premier League - Chelsea v Arsenal - Stamford Bridge, London, Britain - August 18, 2018 Chelsea's Alvaro Morata celebrates scoring their second goal Action Images via Reuters/John Sibley

But such was the strength of Arsenal's rally they could have scored six before the interval, with Pierre-Emerick Aubameyang particularly guilty, blasting one chance over with the goal at his mercy.

In a tighter second half, neither side could carve out as many chances but Alonso settled the game when Belgium winger Eden Hazard, on as a substitute, carved open the Arsenal defence for the Spanish defender to finish in Sarri's first home game in charge.

"It is clear the result is not good for us but the process is continuing," Emery said.

Soccer Football - Premier League - Chelsea v Arsenal - Stamford Bridge, London, Britain - August 18, 2018 Chelsea manager Maurizio Sarri during the match Action Images via Reuters/John Sibley

Soccer Football - Premier League - Chelsea v Arsenal - Stamford Bridge, London, Britain - August 18, 2018 Arsenal manager Unai Emery reacts REUTERS/Toby Melville

(Reporting by William Schomberg, editing by Ed Osmond)

Soccer Football - Premier League - Chelsea v Arsenal - Stamford Bridge, London, Britain - August 18, 2018. Chelsea manager Maurizio Sarri celebrates after Marcos Alonso scored their third goal. Action Images via Reuters/John Sibley

Soccer Football - Premier League - Chelsea v Arsenal - Stamford Bridge, London, Britain - August 18, 2018 Arsenal's Henrikh Mkhitaryan in action Action Images via Reuters/John Sibley

Soccer Football - Premier League - Chelsea v Arsenal - Stamford Bridge, London, Britain - August 18, 2018 Arsenal manager Unai Emery during the match Action Images via Reuters/John Sibley

Soccer Football - Premier League - Chelsea v Arsenal - Stamford Bridge, London, Britain - August 18, 2018 Arsenal's Henrikh Mkhitaryan celebrates scoring their first goal with Hector Bellerin Action Images via Reuters/John Sibley