Let $\mathbb B^n$ be a unit ball in $\mathbb R^n$ and let $F$ be a smooth function on it. Let $\mathbb B^k$ be a unit ball in $\mathbb R^k$. **Question.** Is it true that $F$ has a critical point in the interior of $\mathbb B^n$ if there exists a smooth surjective map $\varphi:\mathbb B^n\to \mathbb B^k$, that has the following properties: 1) For any point $x$ *in the interior* of $\mathbb B^k$ the minimum of $F|_{\varphi^{-1}(x)}$ is attained in the interior of $\mathbb B^n$. 2) The maximum $$\max_{y\in B}\min_{x\in \varphi^{-1}(y)} F(x)$$ is attained in the interior of $\mathbb B^k$. **Comment.** The answer is clearly positive if the differential of $\varphi$ is surjective on the whole ball $\mathbb B^n$. I would be grateful for a reference (or a counter-example which sounds less likely...).