  We solve a problem of Petrova, finalizing the classification of letter
patterns avoidable by ternary square-free words; we show that there is a
ternary square-free word avoiding letter pattern $xyzxzyx$. In fact, we: (1)
characterize all the (two-way) infinite ternary square-free words avoiding
letter pattern $xyzxzyx$ (2) characterize the lexicographically least (one-way)
infinite ternary square-free word avoiding letter pattern $xyzxzyx$ (3) show
that the number of ternary square-free words of length $n$ avoiding letter
pattern $xyzxzyx$ grows exponentially with $n$.
