Arsenal secured their first Premier League win under new head coach, Unai Emery, by beating West Ham United 3-1.
In the opening minutes of the game, Felipe Anderson caused the Arsenal defence big problems all afternoon from the number 10 position and it was the Brazilian who set up Captain Marko Arnautovic to open the scoring.
Emery needed his team to respond quickly and they did, as Nacho Monreal was at the back post five minutes later to control Hector Bellerin pass and smash the ball into the net.
That was meant to be an advantage for Arsenal but it was West Ham who finished the first half better.
Robet Snodgrass almost scored a second goal for the hammers on the stroke of half time as he was free in the penalty area.
The new Arsenal boss responded by introducing Lacazette in place of Alex Iwobi, the Nigerian international at the beginning of the second half.
With 20 minutes remaining, Lacazette crossed the ball into the 18 yard area and Diop who was playing for West Ham for the first time scored an own goal.
It made the score line 2-1 in favour of Arsenal.
Pierrre-Emerick Aubameyang could have made it 3-1 but missed his chance.
It was Danny Welbeck who killed the game by making it 3-1.