18-year-old Saka has started the Gunners' last three games in Lacazette's absence.
Saka said: "Do I feel ready to challenge him? Yeah!
"It's always good to have all our best players available, all of us competing makes us push to play better and better. If one player is injured then others get an opportunity but I want everyone to come back and do the best for Arsenal.
"The boss knows what I can do, what the other players can do. Different games require different players but I feel like I've shown the boss he can trust me. Whatever game he puts me I'll always give it my all.
"It has always been a dream for me. I've been working for this moment as a kid, in the academy. Now I've got to the first team I just want to give it my best to repay the faith the boss has given me."