Timbers unbeaten in last 11 games
Portland (5-1-7) beat United for the first time in four meetings since the club joined MLS in 2011, extending its club-record unbeaten streak to 11 games. The Timbers remain the only undefeated MLS team on the road this season.
"We're going to remain business-like and not get too high or low," said first year Timbers coach Caleb Porter about the unbeaten streak. "It's not like the guys are doing cartwheels in (the locker room). We're happy but we move on."
United (1-9-2) is now winless in its last 10 games -- matching a club record set in 2002 -- and failed to score for the seventh time in 12 games.
Wallace, who began his MLS career with United and also won an NCAA championship at Maryland in 2008, comfortably controlled a strong pass from Frederic Piquionne with his left foot before smashing the ball into the upper left corner of the goal for his fourth tally this season.
"I'm playing free and I'm playing offense instead of defense, which gives me a little bit of space to perform and get more involved in the attack," Wallace said of playing in Porter's system.
Porter said Wallace is having a breakout season.
"I'm just really happy for him because I've always felt he had the talent to be a tremendous player in MLS and he's really shown it this year," the coach said.
Nagbe nearly got the scoring going early on when his shot from in front was tipped over the cross bar by United goalie Bill Hamid in the 17th minute. Hamid finished with three saves.
Given a second opportunity after halftime, Nagbe was able to find his mark. After receiving a looping pass from Ryan Johnson, Nagbe managed to slip behind Brandon McDonald and in front of Ethan White before slotting the ball between Hamid's legs. It was his fourth goal of the season.
D.C. United was only able to put two shots on target, neither of which caused any trouble for goaltender Donovan Ricketts, who came up with the pair of stops.
United's best chance to score came in the 42nd when Carlos Ruiz, starting the first game of his United career, whipped a pass into the six-yard box, but neither Chris Pontius or Kyle Porter could get a touch before Timbers defender Jack Jewsbury cleared the ball.
In the 71st minute, United players begged for an apparent hand ball against Andrew Jean-Baptiste in the 18-yard box but referee Jose Carlos Rivero never flinched and let the game continue.