Wayne Rooney scored twice to lead United to a 4-1 win over Portland. (John McDonnell/The Washington Post)

Those in the Audi Field crowd that were not already standing rose to their feet in the 86th minute Wednesday. D.C. United was on its way to a 4-1 victory over the Portland Timbers, and after extending an extraordinary start to his MLS career, Wayne Rooney was preparing to exit.

He handed the captain’s armband to Steve Birnbaum, and with the roars intensifying, the English striker welcomed his replacement, Darren Mattocks, and accepted congratulations from Coach Ben Olsen and the assistants.

Three days after a breathtaking sequence that produced a dramatic triumph, Rooney was at it again, scoring twice as United recovered from a first-half deficit and blasted a championship contender in front of 18,219 spectators.

Rooney scored the tying goal just before halftime, and after the first pro goal by defender Oniel Fisher, he deposited an immaculate free kick into the net.

United (6-9-6) is unbeaten in four straight, 4-1-0 at the new venue and 4-2-1 since Rooney’s arrival. Amid a pivotal eight-day stretch, D.C. on Wednesday passed three teams to jump from last to eighth place in the Eastern Conference and pull within six points of the playoff threshold.

“He is constant,” Olsen said of Rooney’s influence. “His engagement throughout the game is at such a high level. He doesn’t take a play off. He is constantly in the right spot. He consistently makes the right play — and he can also score a few goals now and then.”

Rooney, who has posted three goals and three assists in seven appearances, likes the team’s direction.

“The more games we play together, the more we understand,” he said. “The players have been fantastic. They’ve helped me settle in really quickly. We are getting a better understanding every day in training and on the pitch every game. I’ve always been a player who can pick up players’ abilities and qualities fairly quickly in how they want to play.”

Besides the growing momentum, D.C. has played at least two fewer matches than the rest of the Eastern Conference and will host 10 of its final 13 games. Next: the seventh-place New England Revolution on Sunday night at Audi Field.

Portland (10-5-7) has lost two straight since forging a 15-game unbeaten streak, the longest in the league this year.

This match marked the return of goalkeeper Bill Hamid, who was reacquired last week on a 1 1/2-year loan from Danish club Midtjylland. Unable to earn regular playing time in his seven-month stay overseas, Hamid had sought a homecoming to the club where he launched his career in 2009.

In Hamid’s first D.C. appearance since September, the supporters’ groups behind the north goal chanted, “Bill … Hamid … Bill-Bill Hamid!” over and over again.

Hamid was tested several times in the first half, conceding a goal in the 35th minute.

Sebastian Blanco made Russell Canouse look silly with a tight cutback just beyond the penalty area. He supplied Andy Polo on the left side of the box for a low cross that Samuel Armenteros one-timed past Hamid from 11 yards.

United was fortunate to remain within a goal as Hamid came off his line to deflect Armenteros’s running header on Blanco’s elegant cross.

About two minutes before the break, United struck back.

With Yamil Asad in possession, Rooney began his run, pulling from Diego Chara while pointing to the open grass in front of him. Asad threaded a wonderful pass through traffic. Rooney met the ball in stride and, with a bit of an angle with which to use, one-timed a low, eight-yard shot past sliding goalkeeper Jeff Attinella.

He took his shot at almost the same spot on the field where Luciano Acosta had headed in Rooney’s sensational pass for the game-winner against Orlando City on Sunday.

Intermission failed to disrupt United’s rhythm and momentum.

Less than two minutes into the second half, Acosta’s dazzling footwork drew four defenders, then another and another. With Portland preoccupied, Fisher pressed forward from his right-back position. Acosta pushed a diagonal ball into Fisher’s path for a 10-yard effort that struck the base of the far post and traced the goal line before breaking the plane.

How stunning was this goal-scorer? Fisher, acquired from Seattle this preseason, recorded his first league goal in 45 appearances. (He has one career assist.) The Jamaican didn’t score in 23 games with Seattle’s second-division club, either, but did strike three times at the University of New Mexico.

United’s confidence in the attack continued to surge. In the 66th minute, on a breakout with Paul Arriola, Rooney attempted an audacious chip that beat Attinella but kissed the crossbar.

Two minutes later, he was back on target.

Rooney was awarded a free kick from 25 yards, and the crowd buzzed with anticipation as he stood over the ball. He can’t place a free kick with the precision of David Beckham, his former English teammate, but with his accuracy from this distance, Attinella wouldn’t have a chance. He didn’t.

Rooney lifted the ball over the wall and beyond Attinella’s reach, placing it into the right side of the net.

“The goalkeeper was a bit far over,” he said. “He left a big gap. I thought I could get it over the wall and on target and give myself a chance to score.”

Said Canouse: “It’s exciting to share the field with him because you know he has the quality to hit them in at any time.”

Mattocks, who lost his starting job when Rooney arrived, capped the victory with a 65-yard run and finish in stoppage time.

“We’ll be relieved when we start to move higher and get above that playoff line,” Olsen said. “We’ve got a long way to go. We can’t get caught up in the emotion of these two games. … We talked about nine points [from three matches] this week. That’s the goal. We got six of them, and we’ll go for three more Sunday.”