The Gunners lost 0-3 to rivals Chelsea at the Emirates on Sunday.
Sagna told L’Equipe: “It was like our match against Sunderland, we could not really create any opportunities.
“The absence of Van Persie has weighed a lot, we have to find a solution.
“Now we can’t fool ourselves, the gap was too large between the two sides. Chelsea were stronger. They were better in the challenges, possession of the ball, passes.
“Last season we got a lot of points against Big Four teams but we failed against some ‘minnows’.
“But we missed our match. There is a lot of disappointment.
“Anyway, we can’t remain focused on that, otherwise we could sink lower.
“We have a postponed match that we must win. Then, the situation could quickly change.”
