The Capitals vanquished their postseason arch-nemesis, eliminated their second-round roadblock and ended a 20-year drought between conference finals appearances for D.C.’s four major professional sports teams with Monday night’s series-clinching win against the Penguins. That automatically qualifies Washington’s 2-1 overtime triumph as one of the biggest wins in D.C. sports over the last two decades, a list that has been limited mostly to early playoff rounds for D.C.’s Big Four.

But everything about it — the undermanned lineup, the goaltending brilliance, the lucky pings, the gritty persistence, the extra time, the Russian-combo winner — made this just unimaginably blissful for long-suffering fans.

And the entire experience got us thinking: What other wins would crack a list of D.C.’s best in recent (or not so recent) years? Before the Capitals took care of business, we asked and you answered. The following was compiled based off some of your most common responses. There is recency bias in all of this, but at first blush, Evgeny Kuznetsov’s game winner has to be a contender for the top of this list.

Monday’s win was the biggest in D.C. sports since …

… John Wall and the Wizards beat the Celtics in Game 6 of last year’s second round.

Wall jumped on the scorer’s table, tugged at the front of his jersey and shouted “This is my city!” after his three-pointer with less than four seconds remaining helped Washington force a Game 7 back in Boston.

“The NBA world wanted to see it,” Wall said after scoring 26 points. “Both teams wanted to see it. It’s only right.”

The Wizards lost Game 7 on the road, but Wall’s heroics brought the franchise as close as its been to the Eastern Conference finals since 1979, and his shot will remain a part of D.C. sports lore. Just look at photo above.

… the Redskins defeated the Cowboys in the 2012 regular season finale.

Led by rookie quarterback Robert Griffin III, the Redskins beat the Cowboys, 28-18, at FedEx Field to clinch Washington’s first NFC East title in 13 years.

Griffin only had 100 yards passing, but his third-quarter touchdown run put the Redskins ahead for good. Fellow rookie Alfred Morris carried the load for the Washington offense, with 200 yards rushing and three touchdowns.

“I’ve been waiting for this my whole life,” Redskins fan Samantha Gordin, 23, who had yelled the entire game with her cousin, Dana, from seats that had been in her family for three generations, said after the win. “RGIII has brought what the Redskins needed. And he has brought Redskins fans back to where we deserve.”

… Jayson Werth hit a walk-off home run in Game 4 of the 2012 NLDS.

The Nationals trailed the Cardinals two-games-to-one in their best-of-five National League Division Series and entered the bottom of the ninth inning of Game 4 with the scored tied 1-1. Werth, who led off the inning, ensured there would be a decisive Game 5 by launching Lance Lynn’s 13th pitch of the at-bat into the visitors’ bullpen.

“We get to play tomorrow,” Werth said afterward. “That’s the best part.”

The Nationals were eliminated the following day after blowing a 6-0 lead, but the “Werthquake” remains one of the greatest moments in Nationals history. An image of Werth completing his home run trot by jumping on home plate was featured on the back of the main scoreboard at Nationals Park for the last five years.

… Sergei Fedorov beat the Rangers in 2009.

A D.C. hockey crowd has seldom been louder than it was after Sergei Fedorov scored with five minutes remaining in Game 7 of the Capitals’ first-round series against the Rangers in 2009.

“It was a two-on-two in their zone,” the 39-year-old Fedorov said of his game-winning goal, which broke a 1-1 tie and helped Washington complete a comeback from 3-1 down in the best-of-seven series. “Not much else going, so I decided to shoot. I knew the defense was giving me short side, so I shot it top shelf.”

It was the Capitals’ first playoff series win since 1998.

… Georgetown advanced to the Final Four in 2007.

In just his third season at the helm, John Thompson III led the Hoyas to their first Final Four in 22 years.

“I’m so proud of these guys,” Thompson said after second-seeded Georgetown overcame an 11-point second-half deficit to defeat top-seeded North Carolina in overtime in the East Region final. “They’ve kind of played this year out in many ways as I thought it would. … I knew we had a chance to be very good by this time of year.”

Thompson and his father, coaching legend John Thompson Jr., became the first father-son duo to coach in the Final Four. Big John was courtside for the Hoyas’ win over the Tar Heels, doing a radio broadcast.

… George Mason advanced to the Final Four in 2006.

Including college teams on this list is questionable because Washington’s loyalties are so divided, but for a few weeks during the 2006 men’s basketball tournament, everyone, it seemed, was a George Mason fan. (Except for alums of some basketball blue bloods.)

The 11th-seeded Patriots knocked off sixth-seeded Michigan State, third-seeded North Carolina and seventh-seeded Wichita State en route to the regional final against top-seeded U-Conn. at what was then known as Verizon Center. George Mason beat the Huskies, too, becoming only the second double-digit-seeded team to advance to the Final Four.

“It was like a dream come true,” said George Mason senior guard Lamar Butler. “I used to dream about that when I was a little kid, in front of my home town, home fans, my family. It’s indescribable.”

The dream died with a loss to eventual champion Florida in the semifinals, but George Mason’s run ranks as one of the most shocking in sports history.

… D.C. United won the 2004 MLS Cup.

D.C. United has won four MLS Cups since 1996, which is four more championships than the Capitals, Nationals, Redskins and Wizards have won during that time. After winning three of the first four titles in league history, D.C. United went four years without appearing in the championship game. That made the franchise’s most recent title, in 2004, especially sweet.

“This is the most special one for me,” midfielder Ben Olsen said afterward. “It became almost commonplace, where we were winning all the time. To have that feeling taken away, to sit for more than three years and nothing happens, it just makes you explode.”

United scored three goals in seven minutes during the first half and held on for a 3-2 win over the Kansas City Wizards despite playing the final 32 minutes a man down after defender Dema Kovalenko was issued a red card for an intentional hand ball.

… Maryland won the 2002 NCAA men’s basketball title.

For some D.C. sports fans of a certain age, Maryland’s NCAA title in 2002 remains the high-water mark of the past two decades. Led by seniors Juan Dixon, Lonny Baxter and Byron Mouton, and junior point guard Steve Blake, the top-seeded Terps defeated Kansas in the semifinals before beating Indiana, 64-52, in an ugly championship game.

“I feel like I’m dreaming right now because I’m part of a national championship team,” Dixon, who was named the Final Four’s most outstanding player, said. “It’s a great feeling man. I’m speechless.”

“I’m very happy,” Maryland Coach Gary William said. “It was a thrill, there’s no doubt about it. But I’m really tired. … I’m just so happy for the players, to see what they did. … Those guys just did it.”

… the Capitals clinched their only Stanley Cup Finals appearance in 1998.

Before Monday, the Capitals, Nationals, Redskins and Wizards were a combined 0-13 in their last 13 attempts to clinch a berth in a conference final since the Capitals closed out the Senators in the second round in 1998. That year, the Capitals advanced all the way to their first and only Stanley Cup finals, where they were swept by the Red Wings. Still, it was a thrill just to be there.

“It’s been a long time coming, to get the chance to win the Stanley Cup championship,” Capitals captain Dale Hunter said after Joe Juneau’s overtime goal in Game 6 against the Buffalo Sabres clinched the Eastern Conference title. “It’s just an unbelievable feeling.”

“I’ve lived in this area all my life and I’ve watched the Caps since I was little,” 25-year-old Capitals fan Jennifer Pennybacker told The Post before the game. “I hope they don’t break my heart. I do have a bad feeling about this game.”

The Post checked back in with Pennybacker after Juneau’s game-winner.

“I’m in shock. They proved me wrong,” she said. “This is amazing. It’s a new day.”

… the Redskins won Super Bowl XXVI.

Given that the Capitals’ prior Stanley Cup run preceded the Ovechkin-fueled “Rock the Red” era that transformed D.C. into the hockey-loving city it is today, there’s a case to be made that Monday’s win was the biggest since the Redskins’ last Super Bowl title in January 1992.