“Everything is turned up now,” D.C. United Coach Ben Olsen said. “It’s nice to be in that moment and nice to see our players experience it. It’s important for us, no matter what happens in these playoffs, to play at this level and continue moving forward as a club.” (Ned Dishman/GETTY IMAGES)

Ben Olsen was at a gala early last month at the National Building Museum, sporting black tie and sneakers to fit the theme, when he received a text message from D.C. United’s athletic trainer. Dwayne De Rosario, the player for whom Olsen was accepting an award that evening, had just injured his left knee playing for Canada’s national team.

Party over.

One year and one day earlier, another key player, Chris Pontius, had fractured his right leg. United was never the same, missing the playoffs for the fourth consecutive year, an infamous record for a club that has won four Major League Soccer titles.

“I was hoping Dwayne would be back in a week or two,” Olsen recounted this week, “but I had a sense it wasn’t going to be great news.”

It wasn’t. De Rosario would miss the remainder of the regular season, leaving United to begin another short-handed and, to many observers, futile trek to the playoffs. The club was in a 2-5-2 rut; this setback would seal its fate.

But what unfolded over the subsequent six weeks defied the dark forecasts and, in the process, breathed life back into an organization that had been almost forgotten in both the thriving league and in an increasingly bubbly sports town.

Despite the absence of the 2011 league MVP, United is unbeaten in six matches, capped by last Saturday’s 3-2 victory over Columbus that ended a five-year playoff drought.

“A lot of things are coming together,” team president Kevin Payne said. “It’s definitely something the organization needed.”

United (17-10-6, 57 points) will conclude the regular season Saturday afternoon at Chicago, needing just a draw to clinch the No. 2 seed in the Eastern Conference behind Sporting Kansas City. A loss to the Fire (17-11-5, 56) would probably relegate D.C. to a first-round match at RFK Stadium on Wednesday (hurricane permitting).

Victory would secure the highest point total in the club’s decorated history (albeit in a season with two more games than in most other years). United would also lock up the third-most points in the 19-team league, enhancing its chances of a berth in the CONCACAF Champions League, an international tournament involving the region’s elite clubs.

“I am not going to sit here and say we are the greatest team in the league right now,” said Olsen, whose squad is 14-2-3 against non-playoff teams but winless on the road against postseason-bound foes (as Chicago is). “But we have shown an ability to beat teams at our level or hard on their luck. And that is an important thing to do.”

De Rosario’s injury had created a tipping point: Would United regain its balance or fall into another late-season abyss?

“We had to get the guys to understand we were a good team with DeRo, and we can still be a good team without him,” Josh Wolff, a veteran forward and assistant coach, said of a team that was in first place for a month during the summer.

United responded with four victories and a draw — each a grinding, industrious performance against non-contending teams — before vanquishing Columbus last week.

United was among MLS’s highest-scoring teams, but without De Rosario’s creativity and game-changing prowess, Olsen questioned the sustainability of a proactive approach.

The other option was employing conservative tactics.

“It’s not in our DNA to sit back, defend and counterattack,” Olsen said. “The goal is to entertain and play attractive soccer. Maybe we could have still done it. I don’t know. But we had to focus on defending.”

“We went boring,” he added, “and we won.”

And they continued to win, thanks, in large part, to defensive stability. During the six-game surge, United has conceded four goals. Goalkeeper Bill Hamid, 21, is making fewer youthful errors and more critical saves. Center backs Brandon McDonald and Dejan Jakovic have forged a balanced partnership.

And outside backs Andy Najar and Chris Korb have thrived in new positions. Najar, a natural attacker, played on the midfield flank before moving to the right side of the backline. Korb was a part-time starter at right back until left-side fixture Daniel Woolard was sidelined in August with a concussion.

Depth was not limited to defense. Built to endure a 7½ -month regular season, the roster has afforded Olsen with numerous options. Twenty-three of 26 eligible and healthy players have started. Seven of last weekend’s starters were not in the projected lineup in training camp.

“I had people come up to me asking, ‘Oh man, you lost your best player, what are you going to do now?’ ” defender Robbie Russell said. “It was almost like a quick emotional blip. We felt [bad] DeRo went down but we knew if we played solid defensively, we would win those closer games.”

United has accomplished it without leaning on marquee players. None of the three highest wage-earners at the beginning of the year start any more: Aside from De Rosario, forward Hamdi Salihi and midfielder Branko Boskovic have become role players.

A rookie (Nick DeLeon) and a pair of journeyman midfielders (Marcelo Saragosa and Lewis Neal) scored against Columbus last weekend. Their average base salary: $53,000.

“It was like a switch turned on in everyone’s head and we just find a way to win,” Jackovic said. “A lot of these close games last year, we would find a way to lose.”

From the start of the campaign, Olsen also emphasized the need to reestablish home dominance. After losing its opener, United is 12-0-4 at RFK for a league-best 40 points. The previous two seasons, D.C. earned 30 of a possible 96 points in Washington.

The reward was a long-awaited return to the playoffs.

“Everything is turned up now,” Olsen said. “It’s nice to be in that moment and nice to see our players experience it. It’s important for us, no matter what happens in these playoffs, to play at this level and continue moving forward as a club.”