D.C. United midfielder Luis Silva, shown earlier this season, has scored a goal in three consecutive matches after his early goal in a 3-1 victory over Montreal on Saturday. (Nick Wass/AP)

Ben Olsen began removing his most effective attackers midway through the second half of a tied match Saturday at RFK Stadium. They were not hurt and he was not upset with them. But with D.C. United’s playoff hopes long gone and priorities shifted to the U.S. Open Cup, Olsen started resting key players ahead of Wednesday’s tournament semifinal at Chicago.

In doing so, Olsen risked yet another regular season defeat. Instead, the first substitute, Conor Doyle, responded with a 68th-minute goal and assisted on Jared Jeffrey’s late clincher in a 3-1 victory over the Montreal Impact before 12,354.

“It was just one of those nights where everything you wanted to get out of a game happened,” Olsen said.

It’s rare when United (3-15-4) gets anything out of a game. But on this rainy night, D.C. dictated terms, posted multiple goals for the first time in regular season play in 31 / 2 months and provided relief to three regulars without losing a beat.

Each goal was scored by a young American who joined the squad in the past month: Luis Silva, in a trade with Toronto FC; Doyle, on loan from England’s Derby County; and Jeffrey, as a free agent from German club Mainz.

Silva, 24, and captain Dwayne De Rosario worked well together in the attack before departing within five minutes of one another. Doyle, 21, replaced De Rosario and promptly scored the first goal of his injury-plagued first-team career.

“It’s been a long time, it’s been a tough road,” said Doyle, who served three years in England. “I’ve been frustrated. I have been down a lot. To get that goal is special.”

In stoppage time, he embarked on a breakaway from midfield and graciously passed to Jeffrey, 23, a fellow graduate of the Dallas Texans youth club. “He has played 90 minutes and ran that far,” Doyle said. “I wasn’t going to let him not score.”

Aside from gaining a victory and resting regulars, United established a fluid rhythm among players who, because of injuries, have not partnered often this summer. The hope now is that a teaspoon of momentum will carry into the Open Cup.

“It’s good to get this confidence before the semifinal,” defender James Riley said. “A lot of young guys put in some good shifts. We’ve been trying all year to develop rhythm, to develop connections. Tonight it felt good.”

Riley supplied Doyle, crossing from the left wing. Making a near-post run, Doyle used a clever touch at the six-yard box to beat Troy Perkins.

United had taken its first lead in the 19th minute. At the end of a quality build-up, Silva brought down a deflection in the box and cut twice before tagging an angled shot from 10 yards for his third goal in three matches.

Perkins kept the Impact (10-6-5) close with several good saves, and in the 52nd minute, Jeb Brovsky worked a sweet combination with Davy Arnaud and picked out the far corner from eight yards for his first goal in 73 regular season games.

Despite Bill Hamid’s return from the U.S. national team, Joe Willis started in goal. Olsen said he will receive Wednesday’s assignment as well — reward for anchoring United’s first three Open Cup matches.

United notes: Chris Pontius, Carlos Ruiz, Lionard Pajoy, Marcelo Saragosa, John Thorrington, Casey Townsend, Lewis Neal and Michael Seaton were not available because of injuries. . . . One year removed from Bethesda-Chevy Chase High, midfielder Collin Martin made his regular season debut.

SKY BLUE 1, SPIRIT 0: In Piscataway, N.J., Monica Ocampo’s goal in the 58th minute extended Washington’s winless streak to 0-12-1. The Spirit (1-14-4) will play its last three NWSL matches at Maryland SoccerPlex, starting Wednesday against Chicago.

RED BULLS 3, SPORTING KANSAS CITY 2: Lloyd Sam had a goal and an assist after coming in as a second-half substitute as visiting New York claimed first place in the Eastern Conference.

Sam entered in the 60th minute with the score tied at 1. He assisted on Fabian Espindola’s go-ahead goal in the 63rd minute and then made it 3-1 in the 69th with a counterattack goal.

DEMPSEY HEADED TO MLS: Clint Dempsey is ending his six-year spell in English soccer to return to MLS. Dempsey, 30, played for the New England Revolution from 2004-’06 before joining Fulham in 2007. He moved to Tottenham last summer and scored 12 goals in 43 games. Tottenham didn’t say what team Dempsey was going to, but reports had him linked to the Seattle Sounders.