Howie Kendrick calls his game-winning grand slam in the 10th inning vs. the Dodgers the best moment of his career. (1:19)

The Washington Nationals overcame a slow start and long odds to reach the National League Championship Series and are now the favorites to reach the franchise's first World Series.

The Nationals stunned the Los Angeles Dodgers with a late-inning rally in Wednesday's decisive Game 5 victory to advance to the NLCS against the St. Louis Cardinals.

At Caesars Sportsbook, the Nationals opened as -120 favorites over the Cardinals in the NLCS.

Washington was considered a contender entering the season but got off to a disappointing start. The Nationals were 19-31 in late May and were listed as a 70-1 World Series long shot at that point at SugarHouse sportsbooks in New Jersey and Pennsylvania. They are 7-2 now at SugarHouse.

The Nationals winning the World Series would be a boon for some sportsbooks and costly for others. Entering the postseason, only the Tampa Bay Rays had attracted fewer bets to win the World Series at William Hill sportsbooks. There were some big World Series bets on the Nationals, though, including a $15,000 wager in October when Washington opened at 22-1 at William Hill. That ticket would pay a net $330,000.

Before the season, a bettor at DraftKings sportsbook placed three World Series bets on the Nationals, totaling just under $5,000, for a chance to win $102,476 if Washington wins it all.

Jeff Davis, head of risk for Caesars Sportsbook, told ESPN that Washington winning the World Series would be an "incredible" result for his shop. The Nationals also are the best possible result for Las Vegas sportsbook operator CG Technology.

However, the Borgata sportsbook in New Jersey said it is facing a "$200,000" net liability on the Nationals in its World Series futures market.

"They are [the] biggest loser in our book, more than the Yankees," Darren Darby, head of sports at Roar Digital, which operates the sportsbook at the Borgata, told ESPN in a text message. "Astros and all others are winners for us."

The Nationals were facing long odds Wednesday, trailing the Dodgers 3-1 entering the eighth inning, with Los Angeles ace Clayton Kershaw in the game. Bookmaker William Hill had the Nationals as 10-1 underdogs to pull off the comeback.

Washington's Anthony Rendon and Juan Soto led off the inning with back-to-back home runs off Kershaw to tie the score, and Howie Kendrick hit a grand slam in the 10th inning to help send the Nationals to the NLCS.

A bettor at FanDuel's sportsbook placed a $2,000 bet in-game on the Nationals at 7-1 when they were down 3-0 to the Dodgers. The bettor won a net $14,000.

The Astros turned back the Tampa Bay Rays 6-1 in Game 5 of their division series to set up a titanic showdown with the New York Yankees in the ALCS.

Houston furniture store owner Jim "Mattress Mack" McIngvale placed another $1 million wager on the Astros to win Game 5 of the ALDS at William Hill US on Thursday, sources confirmed to ESPN. That put him at $1.5 million on Houston to win Game 5. He won his two Game 5 ALDS bets and netted nearly $585,000.

He has now placed nearly $8 million in bets on the Astros in an effort to mitigate potential losses from a promotion he is running. McIngvale also has a $1 million bet on an AL team winning the World Series.