Robbie Russell (3) of D.C. United and Brandon McDonald, right, celebrate a goal against FC Dallas. (Rob Carr/Getty Images)

For weeks, D.C. United Coach Ben Olsen had preached patience with his winless MLS club. Once the players bonded and built a rhythm, he pledged, United would fulfill its promise and show tangible strides.

The breakout came Friday night.

And for the first time since last September, United assembled a well-rounded performance in a 4-1 victory over FC Dallas before 13,169 at RFK Stadium.

For a change, it wasn’t all about Dwayne De Rosario, the 2011 MLS most valuable player. Maicon Santos, playing against his previous team, scored twice and added an assist and rookie Nick DeLeon added a goal and an assist for United (1-2-1), which scored just once in the first three matches.

DeLeon and Danny Cruz, United’s second-choice flank players at the start of the season, were lively and influential. De Rosario, in the hub of the attack, had his finest outing of the spring with two assists. And Joe Willis, starting in place of the injured Bill Hamid, made two outstanding saves in the early stages.

Maicon Santos (29) of D.C. United is mobbed by teammates after scoring a goal against FC Dallas. (Rob Carr/Getty Images)

“It’s still building, but a win like this definitely helps confidence,” De Rosario said. “We’ve got a good thing going right now, so we just have to maintain it, keep our focus, not get beside ourselves.”

Tied at halftime, United scored three times in 13 minutes — each goal coming at the end of sharp buildup and service.

“The team is starting to connect and learn each other’s habits,” said DeLeon, a first-round draft pick from Louisville and the lone goal scorer in the first three outings. “We’re getting more comfortable. Over time, game by game, we keep getting better.”

Willis was put to the test right away, making one-on-one saves on Ricardo Villar and Blas Perez.

“You don’t make those two big saves early,” Olsen said, “the game is done.”

From there, United grew in confidence. De Rosario smacked a half-volley from 30 yards off the crossbar. Most encouraging, though, United was moving the ball fluidly with one- and two-touch passing and using the flanks effectively.

United went ahead in the 28th minute. De Rosario supplied the ball to Maicon Santos, who was allowed to turn 35 yards from the target. With Cruz drawing Hernan Pertuz out of his teammate’s path, the Brazilian touched the ball twice into space and smashed a left-footed, 25-yarder with ferocious pace and unstoppable placement over Kevin Hartman and into the far upper corner.

Dallas (1-2-1) drew even in the 41st minute on a goal that maybe should’ve been disallowed. Perez was well offside when a teammate’s chested pass skipped off defender Emiliano Dudar’s foot. Perez raced in alone before beating Willis with a low finish.

United was unfazed. Ten minutes into the second half, the attack was flowing again. Hartman stopped Cruz’s bid, defender Zach Loyd cleared Hamdi Salihi’s shot at the left post and Hartman got a touch on DeLeon’s blast, which hit the crossbar.

In the 60th minute, Maicon Santos sprayed the ball wide to DeLeon, who chested it down and, from an acute angle, launched a blistering shot over Hartman.

Six minutes later, DeLeon crossed to Cruz for a six-yard finish, and in the 73rd, De Rosario curled a gorgeous ball to Maicon Santos for an eight-yard header.

Dallas midfielder Daniel Hernandez was sent off in the 77th minute after receiving his second yellow card.

“The chemistry was unbelievable,” Cruz said. “We were really prepared. Three points was very important.”

United notes: Perry Kitchen returned from U.S. Olympic duty and played all 90 minutes in defensive midfield. Kitchen “did not have an easy week,” Olsen said. “He was shot from 10 minutes in. We asked a lot of him today and he gutted it out. I’m really proud of him.”