D.C.United forward Wayne Rooney battles for a shot as FC Dallas midfielder Abel Aguilar defends during Saturday's 1-0 United win.(Geoff Burke-USA TODAY Sports)

With heavy hearts and unwavering resolve, D.C. United continued its meteoric ascent in MLS’s Eastern Conference on Saturday with a dramatic victory that seemed sure of ending in an unsatisfying draw.

Locked in a scoreless deadlock with FC Dallas and needing three points to pass Montreal for the last playoff berth heading into the final stretch of the regular season, Russell Canouse scored in the 86th minute for a 1-0 triumph before 19,610 at Audi Field.

United (12-11-8) extended its unbeaten streak to seven and moved into sixth place, one point ahead of Montreal with two weeks left in the airtight race. Because the Impact has played one more match than D.C., Ben Olsen’s crew could clinch a slot by winning two games over the next eight days (home against Toronto and New York City FC).

The high drama unfolded at the end of an emotional week. Paul Arriola, a stalwart in D.C.'s late-season surge, returned home to California on Thursday after the death of his father. Canouse and Arriola have been close friends since even before joining United last year, and so Canouse scoring his first MLS goal at this time seemed fitting.

“That goal was for him,” Canouse said. “We’ve got to keep going. With Paul or without Paul, we know he will come back and be strong, but we have to stay strong for him.”

The goal sequence began with Wayne Rooney’s free kick from near midfield. As two Dallas defenders rose for a clearing header, Canouse peeled off to the left side. The ball fell to him for a nine-yard volley that smashed off the crossbar.

In the ensuing scramble, D.C.'s Steve Birnbaum knocked the ball off a Dallas player. The ball popped up to Canouse, who, as goalkeeper Jesse Gonzalez and two defenders converged, nodded a slow-moving shot that bounded into the far corner.

How the ball came to him, Canouse said, “Somehow, someone, the ball pushed back to me. I don’t know, an angel or something.”

“Just gutsy stuff from a good-old central Pennsylvania kid,” said Olsen, who is also from the Harrisburg, Pa., area. “He should probably finish it on the first one, but he is a gutsy kid and I’m glad he is rewarded for all the work he has done this year.

“He does so many little things that go unnoticed and has been a big part of this turnaround. Obviously Wayne and [Luciano Acosta] and Bill [Hamid] and some of the bigger names get the credit, but he’s up there with all of them.”

Canouse’s brave header came an instant before Gonzalez smashed into him, leaving a small gash on his nose.

“I thought Gonzalez was going to take my head off,” Canouse said, “but at that point, I didn’t care.”

Aside from Arriola, United lost four players to international duty: Junior Moreno (Venezuela), Ulises Segura (Costa Rica), Darren Mattocks (Jamaica) and Dane Kelly (Jamaica).

Chris Durkin (15th start) stepped in for Moreno, while Zoltan Stieber (20th) replaced Segura. With Arriola unavailable and Nick DeLeon not quite ready to start again after a long layoff, Jalen Robinson (fifth start) filled the right-back role. DeLeon entered in the 54th minute.

Dallas (16-7-9) was missing Reggie Cannon (United States), Carlos Gruezo (Ecuador) and Maynor Figueroa (Honduras).

MLS arranges fewer matches during FIFA fixture windows, but because of a backloaded schedule caused by Audi Field’s midseason opening, United will play twice in or around this current period. Next up is visiting Toronto FC on Wednesday.

The Acosta-Rooney combo was purring right away, the Argentine chipping to the Englishmen behind the defense for a rushed shot that rolled wide in the second minute. A foul on a set piece wiped out a goal.

Dallas had clinched a playoff berth, but with Los Angeles FC in hot pursuit of the top seed in the Western Conference and the two first-round byes unsettled, the visitors were hungry for points.

Their quick-strike capability caused some early duress for United, but as the late-afternoon shadows crept across the field, both sides labored to generate quality chances before halftime.

The threats began to flow in the second half. Asad’s spellbinding footwork threatened to crack Dallas’s stout resistance, but United remained one touch from testing Gonzalez.

In the 62nd minute, Rooney cracked a 35-yard free kick that required a spectacular diving save by Gonzalez. Dallas’s swift counterattack and technical prowess prevented United from committing extra bodies into the attack.

United pleaded for a handball in the 75th, but there was no call and no video replay. In the same sequence, Rooney’s bid from inside the box was deflected off target.

At the other end, Hamid thwarted Michael Barrios’s wicked shot from 22 yards and D.C.'s back line came under increasing pressure. United needed three points, but it couldn’t let one point slip away either.

A draw seemed certain until Canouse’s goal, which extended United’s winning streak to three and its Audi Field record to 10-2-1.

“You want pressure moments,” Rooney said. “You want to feel that pressure, and it’s important. We’ve got that pressure and we’re thriving.”

Asked about his team finishing the job over the next two weeks, Olsen said: “The mentality of this team is pretty good. I keep being a little bit on guard for complacency, but they’re a pretty determined group. I expect them to be excited about where we are at, with the understanding that we’ve got still a few games to really make sure we really control this.”

Note: D.C. players wore armbands in memory of Arriola’s father, Arturo, who died at age 48. A mass is scheduled Wednesday in San Diego.