LOS ANGELES — All-Star shortstop Corey Seager was left off the Los Angeles Dodgers' roster for the NL Championship Series against the Chicago Cubs due to a back injury.

The Dodgers announced Seager's surprise omission several hours before Game 1 at Dodger Stadium on Saturday night. Charlie Culberson, who had 15 plate appearances in the big leagues this season, replaced Seager in the lineup.

"It was just unrealistic to think that I would be able to go," Seager said.

Seager complained of back pain during the Dodgers' NL Division Series clincher in Arizona on Monday after sliding into second base in the first inning. The 2016 NL Rookie of the Year didn't run or participate in team workouts this week, and he had an epidural shot Tuesday.

"It improved, but (not) enough to warrant him being out there," manager Dave Roberts said. "It's still sore. (Seager) hasn't hit, hasn't moved around, and to (decide whether) he can not only take the field but be effective out there, I think that we had to weigh everything."

Instead, Seager likely can't play again this season unless the Dodgers reach their first World Series since 1988. Seager theoretically could be added back to the NLCS roster if a teammate was seriously injured, but Roberts downplayed that possibility before Game 1.

So did Seager, who doesn't even plan to travel with the Dodgers to Chicago for Game 3 on Tuesday.

"You try to be the best (teammate) that you can right now, try to not be a distraction," Seager said. "Try to be as positive and inspirational, whatever you want to say, to help your team right now."

The lower back pain clearly frustrates Seager, who can't understand how it happened on an innocuous play.

"It was a very normal slide," Seager said. "I watched it over and over again to see if I landed awkward, hit awkward. I mean, it was extremely normal. Felt it on the slide right away."

Los Angeles also dropped reliever Pedro Baez from its roster. Culberson and outfielder Joc Pederson were added.

Chicago made only one change from the NLDS, adding right-handed reliever Hector Rondon and removing left-handed reliever Justin Wilson.

Seager led the Dodgers with 159 hits this season, batting .295 with 22 homers and 77 RBIs while playing in 145 games. He went 3 for 11 with four walks and two RBIs in the division series, batting second in the lineup in all three games.

The Dodgers' remaining options at shortstop are centre fielder Chris Taylor and backup infielders Kike Hernandez and Culberson. Roberts went with Culberson, who batted eighth against Chicago left-hander Jose Quintana.

"Obviously, it's a big blow," said Rich Hill, the Dodgers' Game 2 starter. "The guy has fought with us the entire year. It's just an unfortunate thing that happens in sports when you get an injury. We're looking for the other guys to step up with Charlie and C.T, which is great."

Culberson batted .250 at Triple-A Oklahoma City this year and appeared in only 15 games for Los Angeles. He famously homered to clinch the Dodgers' NL West title in announcer Vin Scully's final home game last season.

The versatile Taylor was the Dodgers' centre fielder during the NLDS, but he made 96 appearances in the outfield this season and 44 in the infield, including 14 games at shortstop.

Pederson is batting .071 with no homers since July, but the Dodgers could need him in centre field if Taylor plays shortstop.

Baez didn't pitch in the NLDS against Arizona. Neither did reliever Ross Stripling, who was kept on the NLCS roster. Reliever Luis Avilan appeared to be close to a return from shoulder inflammation, but wasn't ready for the NLCS.

Rondon was the Cubs' closer in 2014 and 2015, but moved to a setup role last season after Aroldis Chapman's arrival. He appeared in 61 regular-season games this year, going 4-1 with a 4.24 ERA in an up-and-down campaign.

Chicago acquired Wilson in a trade with Detroit on July 31, adding a veteran lefty who had 13 saves for the Tigers this season. The Southern California native wasn't great in his two months with the Cubs, posting a 5.09 ERA with 19 walks in 23 appearances.

Manager Joe Maddon chose Wilson for the NLDS over Rondon, only to switch it up against the Dodgers. Chicago has two left-handed relievers on its roster with the removal of Wilson, who pitched once in the division series against Washington, getting two outs in Game 4.

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