Arsenal boss Unai Emery rang the changes from Thursday's Europa League match in Azerbaijan against Qarabag. Aaron Ramsey got it started with a wild bit of skill, and he somehow managed to top that with his finish.
Two unerring finishes from Lacazette either side of an Andre Schurrle equaliser had Arsenal ahead, with Pierre-Emerick Aubameyang netting twice off the bench after Ramsey had scored mere seconds after his introduction.
Frenchman Lacazette claimed the opening goal of the London derby at Craven Cottage when he spun on Nacho Monreal's cutback before drilling the ball past Marcus Bettinelli.
Fulham are searching for their second win since promotion from the Championship.
Aubameyang sealed the victory in style, collecting Bellerin's cross and firing left-footed beyond Bettinelli on the turn, before striding onto Ramsey's pass and drilling into the bottom-left corner in injury time.
While most people do not expect Arsenal to challenge Manchester City and Liverpool for the title, Iwobi insisted the team's chances should not be dismissed. But they showed the quality, the pace, the strength too'. He only lasted 54 minutes.
'It is very hard but we must prepare, continue improving and show big commitment'.
Keown admits he is surprised to see Danny Welbeck being handed his first Premier League start of the season and Henrikh Mkhitaryan make his first league start since August 25.
Barkley, who signed for Chelsea in January from Everton, tapped in the second from Olivier Giroud's acrobatic cross before Hazard played in substitute Alvaro Morata to seal the win in stoppage time.
After the worldwide break, Arsenal resume their Premier League campaign at come against Leicester City on October 22, before a Champions League clash away at Sporting Lisbon and a London derby with Crystal Palace.