Fulham started brightly enough on their return to the top flight, but Arsenal were in control after Lacazette’s scrappy opener in eight minutes to become the first player to score the first goal of a Premier League season on two occasions.
Willian almost scored his first Arsenal goal with his first shot, the Brazilian striking the base of the left-hand post from a free-kick on the edge of the box in the first half and later set up goals for Gabriel and Pierre-Emerick Aubameyang in the second half.
The former Chelsea winger is the first player to assist two goals on his Premier League debut for Arsenal since Ray Parlour in August 1992 against Liverpool.
Willian has enjoyed a superb debut alongside fellow countryman Gabriel.