Braves’ Ronald Acuña Jr. makes history as youngest to hit grand slam in postseason

ATLANTA — The Pheñom has officially arrived in the postseason, making history with one swing.

With the Braves facing elimination in Sunday’s Game 3 of the National League Division Series against the Dodgers, Ronald Acuña Jr. connected on his first career grand slam to pad Atlanta’s first lead of this series.

At 20 years, 128 days, he is the youngest player to ever hit a grand slam in a postseason game, surpassing Hall of Famer Mickey Mantle, who did it at 21 in the 1953 World Series.

Los Angeles starter Walker Buehler — who flirted with a no-hitter in the NL West tiebreaker against the Rockies and who entered the postseason with the league’s lowest batting average against (.184) — fell behind Acuña 3-0 after throwing four straight balls to Braves starting pitcher Sean Newcomb to walk in the game’s first run.

Acuña watched a questionable fourth pitch, a 97-mph four-seam fastball, be called for a strike. But when Buehler threw another, Acuña sent it sailing 414 feet to left center with an exit velocity of 109 mph.

That was the 18th-hardest hit ball this season by the NL Rookie of the Year favorite, who is 48th in MLB with an average exit velocity of 114.0.

Follow Cory McCartney on Twitter @coryjmccartney and Facebook. His books, ‘Tales from the Atlanta Braves Dugout: A Collection of the Greatest Braves Stories Ever Told,’ and ‘The Heisman Trophy: The Story of an American Icon and Its Winners.’ are now available.