Suppose that we have a very nice simplicial model category $M$. The simplicial enrichment will be denoted by $map_{M}$. Let $f:A\rightarrow B$ be a morphism in the category $M$ such that $A$ is cofibrant. Suppose that for any fibrant object $R$, the induced map $map_{M}(B,R)\rightarrow map_{M}(A,R)$ is a weak homotopy equivalence of simplicial sets. Do we have that $f$ is a weak equivalence ?