MIAMI — Road kill to road warriors.

The first-place Mets showed Monday night they can hit on the road like they’ve hit at Citi Field.

Now they have to keep hitting — all the way to October.

“This lineup is a lot different now and a lot deeper,’’ hitting coach Kevin Long said Monday night before the Mets pulverized the Marlins, 12-1, at Marlins Park.

A new lineup goes a long way in the NL East.

“We know what’s ahead of us,’’ Terry Collins said. “These guys want to win.’’

The Mets came into the game averaging 2.93 runs per game on the road this season; at home they are averaging 4.09.

A rookie and a rental made all the difference.

Behind the first home run of Michael Conforto’s major league career — a three-run rocket in the second inning — and three doubles and four RBIs by top-of-the-line rental Yoenis Cespedes, the Mets never looked back as they leapfrogged the Nationals into first place in the NL East, the latest they have been in first place since 2008.

“The best feeling in the world,’’ Conforto said of his first home run.

Conforto’s blast traveled 430 feet, the kind of easy, relaxed swing that spoke volumes, a keep-me-in-the-majors swing.

At home the Mets are 38-18. Monday night was only their 18th road victory against 32 losses.

This is a much different lineup, though, than the last one Collins wrote for a road game, a 4-3 loss to the Nationals on July 22.

These Mets are writing a new chapter with the changes made just before the trade deadline when general manager Sandy Alderson added a true slugger in Cespedes to go along with the additions of Juan Uribe and Kelly Johnson.

“He’s the real deal,’’ Collins said of Cespedes.

Counting Conforto, that is four major upgrades.

Baseball is noticing.

Consider this tweet Monday night from @RealCJ10 — that’s former Mets killer Chipper Jones: “One team I would not wanna play the rest of the season…the New York Mets!! They got some fellas that can flat out…BRING IT!!!”

Bring it and swing it.

The night after that one-run loss in Washington, the Mets were shut out 3-0 by the Dodgers at home with John Mayberry Jr. batting fourth and Eric Campbell batting fifth.

That embarrassing lineup spurred Alderson into making moves, capped off by the Cespedes deal.

The Cuban star did not disappoint the fans who came to cheer him in this part of the city known as Little Havana as he tied a franchise record with three doubles. He brings power and athleticism.

“This is why we got him,’’ Collins said. “He’s the guy in the middle of the lineup that can drive in big runs.’’

Let it go, let it flow.

This is the time for the Mets to roll with the hitting show on the road, now that they are facing the soft underbelly of the schedule. They plan on taking full advantage.

There is self-confidence in the room — and not just from the pitchers.

David Wright will drive to Port St. Lucie on Wednesday to begin the next phase of his rehab and is keeping a close eye on the improvements.

“Any time you bring in those types of players with presence, not only does it solidify your starting lineup, but it lengthens your bench,’’ Wright said. “It’s just a different dynamic — especially with the way [Lucas] Duda is swinging the bat now. It seems now there is a serious threat all the way down the lineup and that is the key to having a good lineup.

“You just can’t take one or two hitters out of the equation to completely shut down the offense.”

The Mets believe their time has come because of the deals that have been made and their golden arms.

They’ve made that great pitching pay off at home — and Monday night they showed how explosive they can be on the road.

There’s a new powerful lineup for these new road warriors.