We study the notion of left ϕ-biflatness for Segal algebras and semigroup algebras. We show that the Segal algebra S(G) is left ϕ-biflat if and only if G is amenable. Also we characterize left ϕ-biflatness of semigroup algebra l 1 (S) in terms of biflatness, when S is a Clifford semigroup
