The 2016 Cubs took all of 20 games — three little weeks — to reach the 10-over-.500 mark, then stayed above that level for the remaining five and a half months of the regular season. This year’s team has yet to hit 10 over. Despite that, the Cubs were the first defending World Series champs in six seasons to enter August on top of their division.

Stating the obvious: It’s awfully tough to repeat.

But there’s one big thing about the coming postseason we can take for granted: If the Cubs win the National League Central, as expected, they’ll face the Nationals in the divisional round. And you don’t need me to tell you what that makes this weekend’s three-game series between the Cubs and Nats at Wrigley Field.

Yep: an NLDS preview.

That blast of heat you just felt is the birth of a rivalry.

“Of course we want to be the team knocking them out,” Nats superstar right fielder Bryce Harper said of the Cubs.

“Everyone wants to kick them off the top of the mountain,” said All-Star pitcher Stephen Strasburg.

Full disclosure: Those comments were made during spring training. Still, the Nats were all fired up then to test their championship mettle. That’s no less the case now, as they’re out in front by miles in the NL East.

As exciting as last year’s playoffs were for Cubs fans, it’s probably accurate to say there was an absence of rivalry — and all the delicious things that word entails — when it came to Cubs-Giants, Cubs-Dodgers and even Cubs-Indians.

It could be just different enough with Cubs-Nats to create something special. The hair-flipping Harper, a brilliant talent, was born to be booed by opposing fans. Can’t you hear the “HAR-PER! HAR-PER!” chants now? Not to mention potential “DUS-TY! DUS-TY!” serenades of Nats manager Dusty Baker, who left behind his share of critics from his time on the North Side.

There might not be a living soul who’d bet against the Cubs and Nationals winning their divisions. There’ll be no catching the Dodgers for best record in the league. So, Cubs-Nats it is. Might as well act like it this weekend.

On to the rest of this week’s One Through Nine:

2. Just saying: After their series against the Nats, 27 of the Cubs’ next 30 games will be against teams that currently are below .500.

Translation: They almost couldn’t screw this thing up if they tried.

3. The Cubs have a record of 604-636 (.487) this decade. But you knew that already.

No, really, why bring it up? Because it means they have a chance — a pretty good one, with two-plus seasons remaining — at their first winning decade since the 1930s. And what a decade that was for the Cubs, who won a hair under 58 percent of their games.

Since then: a whole lot of you-don’t-want-to-know.

4. This weekend marks the 17-year anniversary of Sammy Sosa becoming the first Cub with six consecutive 100-RBI seasons. He was on his way to nine straight in all. Average total during that stretch: 127.3.

Lord in heaven, that’s a lot.

Am I the only one who needs a hot shower now?

5. One more thing on Cubs-Nats, come to think of it. You know how Cubs pitcher Jon Lester smacked the first homer of his career on Tuesday? Well, Washington ace Max Scherzer did the same thing the very same night.

Scherzer, you’ll recall, was No. 1 to Lester’s 2 in last season’s NL Cy Young voting. No. 3 was the Cubs’ Kyle Hendricks, who’ll start the series opener between the teams.

Translation: Hendricks is a lock to blast his first home run Friday.

No, not really.

6. The Cubs are 14-4 since the All-Star break. They’ve turned around their season. They’ve opened our eyes to a world of possibilities.

Yawn.

The Dodgers are 20-3 since the break. It’s almost like every single thing anyone else can do, they can do better.

7. The quote of the week, on teammate Dexter Fowler — oops, sorry, make that on Yadier Molina — from Cardinals second baseman Kolten Wong: “He goes, we go.”

8. The White Sox entered Thursday’s game in Boston on pace for a 63-99 (.389) finish. That would equal their 2013 performance, which was a franchise-worst since the 1970 Sox were a preposterously bad 56-106 (.346). But we should talk about something — anything — else.

9. Ryne Sandberg was kind enough to return my call Thursday. Where was he? Where else? At Wrigley.

“I’m in the left-field bleachers,” he said.

Tongue-in-cheek, I asked if anyone had recognized him.

“Nooo,” he said, out-tongue-in-cheeking me.

Who says the guy isn’t funny?

Follow me on Twitter @SLGreenberg.

Email: sgreenberg@suntimes.com

RELATED STORIES

After ‘crazy’ loss, Cubs prepare for Nats in possible NLDS sneak peek

Stay tuned as Cubs monitor August waiver market after productive July