Montreal Impact defender Shavar Thomas, right, heads the ball away from D.C. United forward Maicon Santos in front of the Impact goal during the second half of the 1-1 draw. (Toni L. Sandys/The Washington Post)

With a 1-1 draw against the expansion Montreal Impact on Wednesday night, D.C. United continued a maddening inability to build on a small sampling of prosperity.

Poised to win consecutive MLS matches for the first time in almost three years, United slogged through a disappointing first half and needed a 72nd-minute equalizer by Brazilian striker Maicon Santos to salvage a point before 10,135 at RFK Stadium.

“It’s a disappointing tie, for sure,” Coach Ben Olsen said.

United (2-2-3, nine points) did extend its unbeaten streak to five, but not in the manner it had hoped. The club missed a chance to vault past New York (3-2-1, 10) for second place in the Eastern Conference heading into the first meeting with the rival Red Bulls on Sunday in Washington.

Since defeating Chicago and New York in June 2009, United has failed on 21 opportunities to win back-to-back matches (0-10-11).

“That’s something that has been weighing on our shoulders,” defender Brandon McDonald said. “Letting points go like that, it’s not a good feeling.”

The Impact (1-5-2) had gone ahead in the 68th minute on Bernardo Corradi’s header. After celebrating his 28th birthday with his team-best fourth goal, Santos converted again in the 90th minute but was offside by a whisker on Dwayne De Rosario’s cross into the six-yard box.

United, which has earned just five points from four home matches, was slow and out of sync in the first half — a surprising response after a 2-1 comeback victory at New England on Saturday.

“We just didn’t have that pep, that anger, we needed,” Olsen said. “The second half was great, but it takes me to get them all riled up at halftime to have that type of response. We have to understand you have to bring that every night if you want results. It doesn’t matter who you are playing.”

With a congested schedule and lingering injuries, Olsen shook up his lineup. The effect was fresher players but a lack of harmony in attack and no bite to its game.

The first half ended without a goal, save or imminent threat by either side. United seized the initiative after the break, but Donovan Ricketts made two saves on De Rosario.

Midway through the second half, right back Chris Korb lost track of Corradi at the back post, allowing the Italian striker to head in Lamar Neagle’s excellent cross.

United answered on Santos’s drive from 30 yards. He didn’t present a threat in possession well beyond the penalty area, but after turning into space, he unleashed a low, left-footed shot that beat the outstretched Ricketts to the near corner for his fourth goal.

“I’ve been trying to shoot on goal as much as I can,” he said. “It’s been working.”

On beating Ricketts from distance, “I know him from before. I know the way he works. I know the bad stuff about him,” he said with a laugh.

United wasn’t laughing about the outcome.

“We knew they’d come in here a little desperate and with a real sense of urgency and fight about them,” Olsen said. “We talked about matching that early and not getting bullied around, and [Montreal] did that.”

Forward Chris Pontius tried to accentuate the positive.

“It’s frustrating, but it’s five games in a row where we have gotten points,” he said. “We have shown resilience the last two games coming from behind.”

United note: The supporters’ groups and most other fans fell silent in the 12th minute to honor longtime Barra Brava member Javier “Chico” Solares, who died Tuesday at age 53. Banners were raised: “Fearless in Life,” “Fearless in Death” and “RIP Chico.” The 12th minute symbolized the 12th man (the fans).