This year’s San Francisco Giants-Los Angeles Dodgers division series was billed as a historic clash of dominant regular-season teams, with the two clubs combining to win a record 213 games over the preceding six months. By and large, it has lived up to that expectation: Every win by the perhaps-still-underrated Giants has been followed by a series-tying statement from the Dodgers, leading us to Thursday’s all-or-nothing Game 5.

The immediate stakes of the contest are clear. A win for L.A. would propel it into a rematch of last year’s NLCS with the Atlanta Braves, which the Dodgers won (while erasing a 3-1 deficit) en route to 2020’s championship. A win for San Francisco would put it on the brink of returning to the World Series, bringing one of the game’s most unusual dynasties to perhaps its most unexpected chapter yet.

The symbolic stakes might be just as high. Giants-versus-Dodgers is one of the sport’s oldest and greatest rivalries, with 2,539 matchups spanning over 130 years of history. And this season’s battle felt especially personal. Even if it took them 168 games to do it, a Dodger victory would be the culmination of Los Angeles’s seasonlong bid to hunt down its bitter rival to the north, restoring the pecking order we all assumed would exist between the teams before the season started. For San Francisco, a victory would be one final confirmation of exactly who owned the rivalry, the division and maybe the entire league this season — expert picks and 106 Dodger wins be damned. Plus, spoiling Los Angeles’s attempt to defend its short-season title over a full schedule would give Giant fans plenty to crow about for a long time to come.

And the big-picture stakes for the postseason as a whole could hardly be higher. Before and after each game of the series, either the Dodgers or Giants have been World Series favorites in our forecast model, with Games 3 and 4 causing that status to change hands between Los Angeles and San Francisco (and back again):

Whatever happens in Game 5, the winner will likely be in the driver’s seat for the World Series. Conditional on winning the NLDS, the Dodgers would have a commanding 55 percent chance of winning the championship; for the Giants, that number would be 32 percent. In other words, both clubs’ chances (conditional on winning Thursday) would exceed the current odds for the Houston Astros, the AL’s leading World Series contender at 26 percent.

In that sense, Game 5 is a mini-World Series all unto itself. If it’s not the de facto championship-clincher — a lot can still happen between now and the end of October — it’s a battle to see who will have the title be theirs for the taking (with apologies to the Astros, Braves and Boston Red Sox).

That’s a lot to put on Logan Webb and Julio Urías, dueling starters of the deciding contest, though the two have a combined 0.71 ERA and 1.04 fielding independent pitching in a pair of appearances in the series, with each winning his lone start. And there’s plenty more pitching where that came from, as we would expect from the Nos. 1 (Dodgers) and 3 (Giants) pitching staffs in MLB by wins above replacement this season. But maybe the biggest question is which Dodger lineup will take the field for Game 5. In its two wins, Los Angeles has scored a total of 16 runs; in its two losses, it’s been shut out completely, losing by a 5-0 total margin.

According to ESPN’s Stats & Information Group, the team that scored first has won 21 of the 23 Giants-Dodgers matchups this season, so we might get a sense of who will be title favorites early on. Or Game 5 might buck that trend, as postseason elimination games are wont to do. Either way, one of the biggest narratives of the entire 2021 MLB season — the battle of California behemoths — will see itself resolved Thursday, with huge implications for the championship chase to follow.

Check out our latest MLB predictions.