PHILADELPHIA — Flip that finger, Nick.

The ring one, of course. Nick Castellanos had no desire to turn his moment on second base into a NSFW moment in the postseason.

The All-Star slugger did — with millions briefly confusing the gesture for the obscene finger — direct his ring finger toward a joyous Phillies dugout, sending a message that the defending NL champions are chasing the World Series ring they were denied by Houston last year.

“That’s why we’re playing this month,” Castellanos said.

Zack Wheeler struck out eight in a sensational effort, José Alvarado preserved the lead with a pivotal strikeout and Philadelphia opened a resolute postseason push with a 4-1 win over the Miami Marlins in the opener of their NL Wild Card Series on Tuesday night.

“As soon as I stepped foot out of the dugout to go stretch out there in the bullpen, the crowd went nuts and I got chills,” Wheeler said.

Wheeler quickly started dealing and got the run support needed to put the Marlins on the ropes.

Led by Kyle Schwarber’s 47 homers, the Phillies had six players in the Game 1 lineup with at least 20. But they didn’t need the Schwarbombs and Alec Booms to get the job done, as every starter had at least one hit, without a home run.

Castellanos added an RBI double in the eighth inning to score Bryce Harper — who knocked off his helmet as he steamrolled past a stop sign — and the Phillies moved within a victory of an NL Division Series matchup against Atlanta.

“Bryce does that all the time and he’s miraculously safe more often than not,” Castellanos said with a laugh.

Wheeler allowed one run in 6²/₃ innings.

Craig Kimbrel worked a scoreless ninth for the save.

Phillies fans held signs that read “Un-phinished Business” and they were downright delirious when injured slugger Rhys Hoskins fought back tears and threw the ceremonial first pitch.

Castellanos did, too. He wore Hoskins’ No. 17 on the side of his cap this season in tribute to the first baseman who spiked his bat on a home run last season in an NLDS victory.

“He symbolizes Philadelphia, honestly more than any of the signees that have come here after the fact,” Castellanos said.

The Phillies won 11 postseason games last season, two shy of the ultimate goal and their first World Series title since 2008. The theme of unfinished business — as it is for so many World Series losers — was a key element that permeated throughout the clubhouse this season.

“We’ve got to get back after it this year, and it’s a different team,” manager Rob Thomson said. “I believe it’s a better team, to be honest with you.”

Here they are again, this time with star shortstop Trea Turner, playing big games in October — and with Wheeler in top form.

Wheeler, on the short list of great free-agent signings in team history, brought the heat from the start. He threw nine fastballs in the 97-99 mph range in the first inning, the hardest a pitcher who struck out 212 batters has thrown all season.

The veteran right-hander never backed down as 45,662 fans at Citizens Bank Park roared on every K.

Wheeler’s slider, nasty. His sinker, filthy.

Wheeler is simply grateful for another postseason shot a year after he was lifted with a 1-0 lead in the sixth inning of Game 6 in the World Series against Houston. Yordan Alvarez hit a three-run homer off Alvarado later in the inning and the Astros soon clinched the World Series.

That was last season.

This time, Wheeler took a two-hit shutout into the seventh and was pulled after allowing consecutive infield singles with two outs, the second one by Bryan De La Cruz driving in Miami’s only run.

Alvarado struck out pinch-hitter Yuli Gurriel with two runners aboard to protect a 3-1 lead. The left-hander retired two batters in the eighth, and Jeff Hoffman got the third out of the inning.

The Marlins finished with seven hits.

“I think they know what’s at stake,” manager Skip Schumaker said. “They know what tomorrow means. We’re going to do the same thing we’ve always done.”

Wheeler threw only 46 pitches through four innings — while Marlins starter Jesús Luzardo labored through 90 over the same span.

The 26-year-old Luzardo was raised in South Florida and grew up rooting for Marlins stars such as Juan Pierre and Miguel Cabrera.

Luzardo was 6 years old when he attended Game 3 of the 2003 World Series, won by the Marlins, and was thrilled when he was traded to Miami ahead of the 2021 season.

His first postseason start for his childhood team hardly went as planned.

Johan Rojas, the No. 9 hitter, hammered away at Luzardo with a nine-pitch at-bat for a single that opened the third. He scored on Alec Bohm’s RBI double to left field.

Luzardo gave up run-scoring singles to Bryson Stott and Cristian Pache that made it 3-0 in the third.

“We’ve just got to keep this going,” Harper said. “Leave no doubt.”