He simply could not live with the pace of Danny Welbeck and Alex Iwobi and allowed Lacazette to turn in the box to score his first goal.
But Emery freshened up his side with six changes, although one was enforced as Mesut Ozil was sidelined due to a back spasm, and there were no signs of fatigue as they took the lead in the 29th minute.
Wales boss, Giggs is confident that the player has what it takes to play in any league in the World, stressing that the Gunners will find enough suitors for the player.
Pierre-Emerick Aubameyang scored two goals after coming on as a substitute in the second half.
"Now it's a togetherness, a unity for the fans, the players and the new manager and it's going nicely".
"But I am just thinking about the next match against Leicester at the Emirates, in our home, with our supporters".
Missing journalist reportedly killed in 'barbaric way' at Saudi consulate
On Wednesday, the Turkish foreign ministry summoned the Saudi ambassador and asked for an explanation about the disappearance. Khashoggi was born in the western Saudi city of Medina, revered in Islam as the burial place of the Prophet Mohammed.
Arsenal continued to cause problems and we made it 4-1 with ten minutes to go as Aubameyang controlled Bellerin's cross before firing home on the turn and the Gabon global then made it 5-1 late on after being sent clear by Ramsey. "We knew Fulham play good football and play with a lot of counters, but I think the team played well".
The Wales global looks set to leave the club at the end of the season after contract negotiations broke down but he capped some superb build-up play by steering in a wonderful flick for Arsenal's third goal just 38 seconds after coming off the bench.
[I was pleased] not only with the first XI but with the substitutes.
Aaron Ramsey, who came off the bench in the 60th minute, piled more misery on the opponents with a flawless backheel. He opened the scoring for Arsenal and then got another in the second half to restore their lead after Andre Schurrle had cancelled out his opener. However, they were undone by one of the goals of the season.
"We showed so many weaknesses for this Premier League level". We need their support each match. We finished the game with 21 shots, and the other team nine. They are just two points above the bottom three, too.