  Let $G$ be a $K_4$-free graph, an edge in its complement is a
$K_4$-\emph{saturating} edge if the addition of this edge to $G$ creates a copy
of $K_4$. Erd\H{o}s and Tuza conjectured that for any $n$-vertex $K_4$-free
graph $G$ with $\lfloor n^2/4\rfloor+1$ edges, one can find at least
$(1+o(1))\frac{n^2}{16}$ $K_4$-saturating edges. We construct a graph with only
$\frac{2n^2}{33}$ $K_4$-saturating edges. Furthermore, we prove that it is best
possible, i.e., one can always find at least $(1+o(1))\frac{2n^2}{33}$
$K_4$-saturating edges in an $n$-vertex $K_4$-free graph with $\lfloor
n^2/4\rfloor+1$ edges.
