CHICAGO — All that remains of this NLCS for the Mets is an almost inevitable third champagne celebration in the last month and the hoisting of a pennant.

Unless Cubs president Theo Epstein has another trick up his sleeve — he was Red Sox general manager in 2004, when Boston rallied from three games down against the Yankees in the ALCS to win it all — the Mets are headed to the World Series for the first time in 15 years and looking very much like a potential favorite.

Jacob deGrom moved his team to the brink of nirvana on Tuesday, firing seven strong innings that carried the Mets to a 5-2 victory over the Cubs in Game 3 of the NLCS at Wrigley Field.

The Mets, ahead 3-0 in the series, will try to clinch the franchise’s fifth pennant Wednesday, when rookie Steven Matz faces Jason Hammel. A victory will send the Mets to Kansas City or Toronto for Game 1 of the World Series on Tuesday.

“We’ll feel better after another win,” David Wright said. “The last thing we want to do is start thinking beyond [Wednesday].”

Among MLB teams, only the 2004 Red Sox have overcome a three-game deficit in the postseason. It will be 70 seasons and counting without a pennant for the Cubs, unless they can win four straight.

“It’s not going to be easy, but of course it can be done,” Cubs manager Joe Maddon said.

But Maddon is taking the long view, refusing to pitch one of his horses, Jon Lester, on short rest Wednesday.

“We’ve got to win four games,” Maddon said. “It’s not about [Wednesday’s] game.”

DeGrom improved to 3-0 this postseason — in three starts on the road — by allowing two earned runs on four hits and one walk with seven strikeouts over seven innings. He survived a grueling first in which he threw 29 pitches and allowed a run on Kyle Schwarber’s homer.

“I don’t know why the first inning has been so tough for me,” said deGrom, who rebounded from a rough first to beat the Dodgers in Game 5 of the NLDS.

Daniel Murphy continued his magic by hitting a home run in a fifth straight postseason game, tying an all-time record. Overall, he’s homered six times in eight postseason games.

“I wish I could explain it,” Murphy said. “I would have done it six years ago.”

The Mets all but iced the game with two runs in the seventh. Yoenis Cespedes delivered an RBI single before Lucas Duda’s RBI ground out scored the Mets’ fifth run.

“We’re very fortunate, because the Cubs have played great,” manager Terry Collins said. “They are playing great and we’ve got to come out [Wednesday] and Steven Matz has got to give us a game. Our bullpen is pretty rested and if Steven can get us five or six we’ve got a lot of answers in the bullpen for any matchups we need.”

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The Mets took a 3-2 lead in the sixth on Trevor Cahill’s wild pitch, but lost another run because of the right-field ivy. Wilmer Flores hit a line drive to right that Jorge Soler missed while going for a shoestring catch, and the play was ruled a ground-rule double after the ball rolled into the ivy.

Conforto, who would have scored easily on the play, was sent back to third base as Collins unsuccessfully argued his case. Conforto was then left stranded at third.

Conforto had been struck out to end the inning, except that Cahill’s breaking ball hit the dirt and eluded catcher Miguel Montero, allowing the batter to reach first and Cespedes to score from third with the go-ahead run. Cespedes had stolen third after Duda’s surprising sacrifice bunt moved him to second.
Soler’s homer in the fourth made it 2-2 after deGrom had settled into a groove following the shaky first inning. With one out in the fourth, Soler smashed a 3-1 fastball into the center-field bleachers for his third homer this postseason.

Murphy’s solo homer with two outs in the third against Kyle Hendricks gave the Mets a 2-1 lead. With the blast Murphy became just the second player — joining Carlos Beltran in 2004 — to homer in five straight postseason games.