  The Gr\"{o}tzsch Theorem states that every triangle-free planar graph admits
a proper $3$-coloring. Among many of its generalizations, the one of
Gr\"{u}nbaum and Aksenov, giving $3$-colorability of planar graphs with at most
three triangles, is perhaps the most known. A lot of attention was also given
to extending $3$-colorings of subgraphs to the whole graph. In this paper, we
consider $3$-colorings of planar graphs with at most one triangle.
Particularly, we show that precoloring of any two non-adjacent vertices and
precoloring of a face of length at most $4$ can be extended to a $3$-coloring
of the graph. Additionally, we show that for every vertex of degree at most
$3$, a precoloring of its neighborhood with the same color extends to a
$3$-coloring of the graph. The latter result implies an affirmative answer to a
conjecture on adynamic coloring. All the presented results are tight.
