United’s Andy Najar controls the ball against Sainey Nyassi of New England. (Ned Dishman/GETTY IMAGES)

In its quest to end a three-season MLS playoff drought, D.C. United won’t confront any must-win matches until these searing summer days are a distant memory. But with the club beginning a favorable stretch of the schedule against a listing opponent and needing points at home, Wednesday night’s affair with the New England Revolution carried urgency reserved for later in the calendar.

The moment wasn’t lost on the players, but after watching a wealth of scoring opportunities melt away, United yielded Stephen McCarthy’s 73rd-minute goal off a corner kick and dropped a disheartening 1-0 decision before 15,597 at RFK Stadium.

An early goal would’ve cracked the match wide open, but New England goalkeeper Matt Reis was exceptional and Charlie Davies missed a 44th-minute penalty kick.

“It’s a tough one to take just because of the opportunities we had early to put a game away,” United Coach Ben Olsen said. “If you don’t do that, we’ve all seen the script, right? They got through to the second half with a new lease on life and then they get a set-piece goal — that’s what they do.”

The missed penalty, an effort that sailed well over the crossbar, punctuated a rough evening for United’s leading scorer, who labored to beat anyone with the ball and made insufficient runs without it. He hasn’t scored in the past four matches.

“I hit it good, I just leaned back and it went over,” Davies said. “It was pretty painful to see that go over the bar.”

It was also painful for Davies and United (5-6-8) to see another home game slip away. United is 2-3-5 at RFK, one of the worst marks in the league.

Entering Wednesday’s matches, none of United’s eight opponents until mid-September boasted a winning record and their combined mark was 31-62-63. United has been kicking itself over its inability to win at home and rise in the unsettled Eastern Conference standings, and the Revolution (4-9-7) arrived particularly vulnerable: a 0-6-3 skid, 0-6-3 away record and league-low 16 goals.

United generated four high-quality chances in the first 20 minutes: Dwayne De Rosario poked Andy Najar’s cross just wide, De Rosario whistled a 25-yard effort a whisker over the crossbar, and Reis made terrific diving saves on Davies and De Rosario.

Defender Brandon McDonald rescued United with a superb tackle on Rajko Lekic in the penalty area and Bill Hamid’s assertiveness alleviated another potential problem as he surged off his line to punch away a ball directed at Lekic.

In the final moments of the half, New England’s Pat Phelan blocked Josh Wolff’s cross with his elbow, resulting in the penalty. Davies, though, sent his bid high over the bar, his first miss in five attempts this season.

He said he couldn’t remember the last time he had missed a penalty in his college and pro career.

Reflecting on all the opportunities, not just the penalty, midfielder Chris Pontius said, “If we go up 1-0, the whole game changes and they actually have to come out and attack us instead of sitting back.”

United was back on the prowl after the break but lacked a final incisive pass and began to run out of ideas. New England was comfortable absorbing pressure and waiting for a sliver of opportunity. It arrived in the 73rd minute when McCarthy headed in Chris Tierney’s corner kick from nine yards.

“We put a good effort in for the 45 [minutes], the goal didn’t come, and then physically we tanked,” Olsen said. “I was disappointed we didn’t gut through it a little bit more and find a way to get a result.”

Reis preserved the lead in the 82nd with a splendid foot save on De Rosario’s near-post bid.

“It’s a huge missed opportunity,” Wolff said. “That’s three or four of them at home. We’re going to look back in two months and hopefully we don’t really regret it and miss out on the playoffs because of it.”

United notes: D.C. will take a break from the MLS campaign Saturday when it hosts English club Everton in a friendly. . . . Brazilian midfielder Fred made his final appearance before transferring to Australian club Melbourne Heart. . . . Austin da Luz, acquired from New York this week, made his debut in the 71st minute. . . . New England wore black armbands in memory of Myra Kraft, wife of Revolution and Patriots owner Robert Kraft. She died of cancer Wednesday at age 68.