Lacazette struck in the 2-0 win.
He said, "We were strong defensively, we respected what the coach asked of us and we scored two goals so we're happy.
"We have won the last two or three games, I think we played well today and they're a good team in the Premier League so to win 2-0 on this stage is a really good performance.
On fellow goalscorer Bukayo Saka, he added: "He scored the first goal to help the team to go forward in the game and when I came on I had the chance to score as well so I am happy. My first since we came back from lockdown."