Nationals shortstop Trea Turneris congratulated after coming home in the sixth inning of Sunday’s victory. (Katherine Frey/The Washington Post)

This weekend, the Nationals and Dodgers, with the best records in the National League this season and the best records in the major leagues over the past six years, meet three times at Nationals Park in what may be a preview of the National League Championship Series, including the Sunday night game on national TV.

Stop right there. Back away from the ledge. There’s danger everywhere.

The last thing that the Nats and Dodgers should do is look too far into the future and imagine themselves in an NLCS with a World Series trip at stake. Look at what such premature congratulation has gotten the Nats and Dodgers in recent years: disappointment, chokes and mockery.

The Dodgers have MLB’s biggest payroll and lots of star power. At times, the Nats have thought they had the most talent, whether they really did or not. Yet what these teams have done best is get ahead of themselves and get eliminated.

Their five-game meeting last year was perhaps the best-played and most exciting show these teams have put on in October. They brought out each other’s best. They need to do it again. If they focus on intense, well-played baseball this weekend, maybe they both can sharpen their games — and, boy, do they both need it — so they can survive the first round and meet again.

No team has won the World Series after going through a slump as bad as the Dodgers’ recent 1-16 pratfall. Such gagging sticks in the mind.

The Nats have no idea who they are; they never have been both healthy and in possession of a competent bullpen for one day this season. But with just 16 games left and Bryce Harper still slowly working back toward the lineup, time is running short for collective identity creation.

So far, a pathetic schedule (and pluck) has boosted the Nats to 89-57. They have played only 46 games against .500 teams, six fewer than the next lowest (the Indians).

The Dodgers need an exorcism, the Nationals, a team-is-born narrative. Fast.

L.A. has not been to the World Series since 1988 despite making the playoffs 10 times. The Dodgers aren’t the Capitals in cleats, but they’re working on it.

The Nats have done worse. The past five years, they have been 0 for 3 in division series, plus two years when their preseason-pick teams missed the playoffs.

By 2019, Harper may not be a Nat. How long can Clayton Kershaw, with his achy back, keep monopolizing Cy Young awards? If these teams don’t beat their whammies, this year or soon, they may be remembered as the major chokers of the decade.

Just thought you would like to know. The truth helps.

This series has a fascinating subtext. The Nats have an outside chance to catch the Dodgers for best record in baseball. They trail by ­five   games.

The Nats should hope they don’t catch the Dodgers. It would be a trap.

MLB’s current postseason format has a glitch. A league’s best team (No. 1 seed) must wait three or four days before its first playoff game. Then it plays the elated wild-card winner, which has had only one day off. This year, for the NL division winners, it’s a four-day layoff. This tends to ice hitters — not all of them, but if a couple lose timing or psych themselves out with a blame-the-layoff excuse, then it becomes a self-fulfilling contagious problem.

In 2014, Nats Manager Matt Williams was so worried about such a layoff that he played an intrasquad game to knock rust off his hitters. Did it help? Or just plant doubt? The Nats battered a mostly mediocre Giants staff for a .164 average.

Since the new format arrived, the wild-card winner has a 23-18 record against the “best team” in the league. Small sample but a big worry.

The Nats should prefer things to stay as they are, so they play the Cubs, who also would have a four-day layoff, in the first round. Nothing frees up the nervous system in baseball like a sincere dislike of your opponent. Hello, Cubs.

On the strength of winning one World Series in 108 years, the Cubs now look down their noses at other teams, specifically the Nats. Washington GM Mike Rizzo already plans to put the “Nats will crumble” quote, said by Cubs executive Todd Ricketts to President Trump at the White House, on the Nats’ bulletin board in October, just as he did in June. The Nats will be reminded that the Cubs broke Trea Turner’s wrist with a 96-mph fastball at the end of a series in which he ran wild on them. Oh, it will be a lovely hate-fest.

If the standings Oct. 1 are the same as they are now, not catching the Dodgers may have another benefit for the Nats. They may never play the Dodgers at all. Arizona and Colorado probably will face off in the wild-card game. They hold 11-8 and 9-7 records against the Dodgers this year. The Diamondbacks have clubbed them 99-71. The Dodgers, built on pitching, don’t enjoy visiting either mile-high Denver or the hitter’s heaven in Phoenix.

There’s a final diabolical twist in the current No. 1 seed-vs.-wild card arrangement. The theory is that both wild cards will start their aces against each other, thus “burning” their best pitcher for Game 1 of the LDS. But if your No. 1 and No. 2 starters are excellent and roughly equal, such as the Diamondbacks’ Zack Greinke and Robbie Ray, is it really a disadvantage?

The wild-card winner can give all its starters full rest and use them in this sequence: Nos. 2-3-1-4-2. The No. 1 seed goes 1-2-3-4-1. Parse it out for yourselves if you want with this year’s likely teams. My provisional view is that the postseason has so many off days that most wild-card winners have only small rotation problems. But the idle No. 1 seed always has an ice-the-hitters issue.

This weekend, the Nats and Dodgers, both of whom may win more than 100 games, will foster the subversive narrative that they will or should meet again in October.

Resist the thought. Since the All-Star Game, the Cubs and Nats, not the Dodgers, have the best record in the NL. The Cubs, now healthy and pitching better, have scored 100 more runs than the paralyzed Dodgers since the break.

The Dodgers and Nats should be fun this weekend. But they don’t need to focus on sending a message or scouting each other for a rematch. First, they need to sharpen their games. Then maybe one of ’em actually will be in the NLCS.

For more by Thomas Boswell, visit washingtonpost.com/boswell.