Clayton Kershaw, Kenley Jansen and the Dodgers celebrate after beating the Arizona Diamondbacks, 3-1, to win the National League Division Series at Chase Field on Monday night. (Getty Images)

PHOENIX — The last time the Los Angeles Dodgers departed the lush coastlines of Southern California for the Sonoran desert, it was late August, with temperatures here up in the low teens — as in 113 and 114 degrees Fahrenheit — and the Dodgers melted like ice cream. They didn’t know it at the time, but their three losses to the Arizona Diamondbacks were among the first signs of trouble for a team that was shifting from historically unbeatable to utterly incompetent with unprecedented swiftness.

Late Monday night, as they converged in a scrum near the center of the Chase Field diamond to celebrate their three-game sweep of the Diamondbacks in the National League Division Series, the Dodgers seemed eons removed from those lost days of late summer. The old Dodgers — of June and July, of incomparable weaponry and uncommon swagger, of Bellinger and Turner and Seager — are back.

The Dodgers, better in every facet of the game, dispatched the Diamondbacks with a 3-1 win Monday night in Game 3, behind five solid innings from Yu Darvish, solo homers by Cody Bellinger and Austin Barnes and four innings of exquisite bullpen work, and will head back to L.A. to await the winner of the Chicago Cubs-Washington Nationals series, whom they will host in Game 1 of the NL Championship Series on Saturday at Dodger Stadium. It is the Dodgers’ second straight appearance in the NLCS; a year ago, they lost to the Cubs in six games.

“Eight more wins,” closer Kenley Jansen said, referring to all that is left between the Dodgers and a World Series title. “Just eight.”

That 1-16 stretch the Dodgers endured in late August and September, the one that came out of nowhere when they were 55 games above .500 and ended any talk of them being remembered as one of the greatest teams in history, now looks like an aberration — albeit one that lasted nearly three weeks and forced some serious introspection as the playoffs loomed.

“That’s just the media [talking]. That’s in the past,” Jansen said of the teamwide slump. “We laugh about that now.”

Even as the Dodgers won eight of their final 10 regular-season games — against mostly inferior opponents — they did not make a convincing argument that they were all the way back from their strange, late-season malaise. In these three games against the Diamondbacks, they did. They outscored their division rivals by an aggregate score of 20-11, and defeated three pitchers — Taijuan Walker, Robbie Ray and Monday’s victim, Zack Greinke — who had beaten them late in the regular season.

Desert baseball is a different animal, all burnt orange and Sedona red, mist machines on the sidewalks along Randy Johnson Way, 84 degrees outside at first pitch, but an air-conditioned 74 inside, even with the retractable roof open and exposing the black sky. It’s all vastness and pumped-in snake-hiss noises and thin air that makes baseballs soar to impossible heights, as if the sense of scale is thrown off by all that open space and endless sky.

The Diamondbacks have won a World Series (2001) more recently than the Dodgers (1988) have, but here lately they have had a tough time getting past their older, richer, more glamorous rivals to the west. The Dodgers won 104 games this season and took the NL West title for the fifth straight year, and in two of those seasons, including this one, the Diamondbacks were runners-up. When the Dodgers clinched the division here in 2013, they famously celebrated by jumping into the pool beyond the right-center field fence.

Back when these Dodgers were entering the late-summer tailspin that would last a good three weeks, it was Greinke — their teammate just two years earlier before he opted out of his Dodgers contract at the end of 2015 and signed with Arizona — who handed them the third of their three straight losses here.

On Monday night, though, Greinke struggled to put away hitters, needing 29 pitches to complete a laborious first inning and going to a full count on five of the first eight batters he faced. But he escaped jams, gained strength and held on until two solo homers in a three-batter span — by Bellinger in the fifth and Barnes leading off the sixth — finally spelled the end of his night.

“I could tell by the body language that things were going good. We just wanted one more batter,” Diamondbacks manager Torey Lovullo said of the decision to let Greinke, down by a run, face Barnes leading off the sixth inning. “Unfortunately, it didn’t happen.”

What Greinke did was give the Diamondbacks a chance, if only they could have solved Darvish and the parade of relievers who followed him. There were, in fact, many “if onlys” for the Diamondbacks in this series.

Dodgers starter Yu Darvish delivers during Monday night’s NLDS-clinching win. (Ross D. Franklin/AP)

The Dodgers’ July 31 trade for Darvish was supposed to be the move that elevated them from a regular-season juggernaut to an October one. But the four-time all-star went more than a month without a win around the same time the entire team went nearly three weeks with just one. He rediscovered his form around the same time everyone else did, striking out 21 batters and walking only one over his final three starts, two of them wins.

Darvish’s fastball averaged about 94 mph this season, the highest of his career, but whether because of the dialed-up October adrenaline or the 14-day layoff between starts, Darvish’s heater had some extra giddy-up to it Monday night, sitting at 96 and touching 98. After he struck out the side in the fourth, ending it with a nasty, 96-mph sinker to whiff Arizona slugger J.D. Martinez, Darvish came off the mound howling and fist-pumping.

“The best we’ve seen him since we got him,” Dodgers ace Clayton Kershaw said of Darvish.

When Darvish’s spot in the batting order came around in the top of the sixth, Dodgers manager Dave Roberts allowed him to hit — only to practically sprint to the mound a batter into the bottom half to remove Darvish after the starter threw two straight pitches up near the neck of pinch hitter Christian Walker, with the second of them clipping Walker on the bill of his helmet.

That left 12 outs for the Dodgers’ bullpen to collect, which it did with brutal efficiency: two outs from lefty Tony Cingrani, four from setup man Brandon Morrow, three from Kenta Maeda — a converted starter whose success as a reliever in this series could be a game-changer the rest of this month — and, finally, three from Jansen. The Diamondbacks put only one runner on base in those four innings and managed to get only two balls out of the infield.

At the final out, with Jansen getting Arizona slugger Paul Goldschmidt to chase a nasty, 95-mph cutter well off the plate, the Dodgers streamed toward the mound, hugging one another and donning caps and T-shirts reading “This Team.” They retreated to their clubhouse to spray champagne and beer, but it wasn’t the party-with-abandon look of a group of October neophytes.

It looked like a team that had been through a lot, but that still expected to be here all along.

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