Puig, who batted second and played centerfield in each of the series' first three games, had struck out in seven consecutive at-bats before his sixth-inning triple in Game 3. Puig then struck out in his final at-bat of the game. He has eight strikeouts in 14 plate appearances during the series.
Puig is not injured, Dodgers manager Don Mattingly said.
"He's healthy," Mattingly said, according to Yahoo's Jeff Passan. "It's pretty simple. I just feel like this gives us the best chance to win today."
Shelby Miller will start for the Cardinals. Miller is a righty, and the righthanded Puig is a better hitter against righties than he is against lefties. He batted .307 this season against righthanded pitching and .258 against lefties.
During the regular season, Puig had the eighth-best batting average in the National League at .296. He struck out 124 times, the 22nd-most in the NL.
Puig struggled in August, posting a .216 batting average and .247 slugging percentage. He rebounded in September, though, batting .284 with a .432 slugging percentage.
Puig's hottest month was May, when he batted .398 with eight homers, 25 RBIs and a .731 slugging percentage, but he still struck out 24 times, tied for his most in a single month this season.
The Cardinals can clinch the series and advance to the NLCS with a win. A Dodgers win would send the series back to Los Angeles for a decisive fifth game.
- Dan Gartland