Arsenal spent a club-record £52million to buy Lacazette in July from Lyon, where he found the net 100 times in Ligue 1.
The 26-year-old has adapted quickly to the Premier League too, scoring in wins over Leicester and Bournemouth.
And Kante, who impressed on his first Champions League appearance in Tuesday's 6-0 win against Qarabag, said: "I think maybe in England, you don’t know him very well.
"But in France, he was a very good goalscorer who scored for many, many years and he will be a threat for Sunday’s game.
"We have to be ready to stop him but the most important thing is the team and we need to win."