The teams will play again Saturday in St. Louis.
Andy McDonald assisted on Tkachuk's goal and also produced the game-tying tally in the second period. It was the Blues' third win in four games.
Pekka Rinne stopped 34 shots and pulled off several spectacular saves, but it was not enough to keep the Predators from losing their third straight.
The Nashville goal came from Steve Sullivan in the first period.
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