David Luiz saw red after only 26 minutes on his return to Stamford Bridge as an Arsenal player. Luiz gave Leno a little help to the groud as he was through on goal.
The foul resulted in the Brazilian defender receiving a straight red card and Jorgino converting the spot-kick to give Chelsea the lead.
Chelsea held on to their lead up to the break and by and large dominated the game.
However, they never killed the game off and were punished in the second half with a 64th-minute goal from Martinelli.
The 18-year-old made the most of a N’Golo Kante slip and seized the opportunity to break free and score a cooly finished goal.
Chelsea was not ready to settle for the draw just yet though.
As the end of the game approached and the opportunity arose, and team captain Azpilicueta scored what he thought was the winner for Frank Lampard’s side.
However, the blues switched off again only three minutes later to let the Gunners back in.
This time Hector Bellerin the Arsenal captain showed he can lead his time back from the brink too.
Bellerin took a shot from the edge of the box, that appeared to like power, but it found its way through the box and into the far corner.
Final score; Chelsea 2 – 2 Arsenal.