Mauro Rosales, who had two assists for Seattle, is fouled by Daniel Woolard. (Otto Greule Jr/GETTY IMAGES)

The rain began to fall around halftime Saturday evening, a fitting backdrop for D.C. United’s 3-0 loss to the Seattle Sounders at CenturyLink Field. While 36,242 witnesses rejoiced from start to finish in the commonly wet conditions, United could only hope the steady shower would wash away the memories of an unpleasant visit.

The Sounders hoarded possession, pierced United’s back line and scored two clinical goals before halftime, leaving D.C. drenched in despair. The trio of Alvaro Fernandez (two goals), Mauro Rosales (two assists) and Fredy Montero (one assist, several threats) was spellbinding and incisive.

It was a troubling night all-around for United (8-8-10, 34 points), which watched unfavorable scores arrive from around MLS. Philadelphia (39 points), Houston (39), New York (36), Chicago (30) and Toronto (30) won, further cluttering the Eastern Conference playoff race behind front-runners Columbus (41) and Kansas City (40).

United has played at least two fewer games than all of its rivals, but performances such as Saturday’s do not bode well for a postseason berth.

“I told the guys: ‘It’s done,’ ” Coach Ben Olsen said. “Our focus now is on Wednesday’s game [against Chivas USA at RFK Stadium]. Throughout the season, you’re going to have some games like this. We’re in no position to sit and dwell on things, and I think they know that.”

With Bill Hamid slowed by a strained hamstring, rookie goalkeeper Joe Willis made his third start and was placed under persistent pressure by the Sounders (14-6-9).

“They came out strong and came at us pretty hard. They just kept coming,” Willis said. “They keep the ball well, they move off of it well. At times it can be mesmerizing watching them pass.”

United, which entered the night with only one loss in the previous nine away matches, hoped to capitalize on Seattle’s hectic schedule, which included a CONCACAF Champions League match Wednesday in Costa Rica. But playing its first game without attacker Chris Pontius (broken leg), United allowed Seattle to dictate terms and labored to gain traction in attack on the artificial turf.

Charlie Davies, who benefited from Pontius’s brilliance last week in recording a hat trick, wasn’t a factor and Dwayne De Rosario labored to exert influence.

In the 35th minute, the Sounders struck. From midfield, Brad Evans targeted Rosales, who bumped Daniel Woolard out of the path and let the ball roll into space. Second-year forward Mike Fucito ran onto it, raced past McDonald and beat Willis with a low, 15-yard effort to the far corner.

Two minutes of first-half added time provided Seattle with two additional scoring opportunities. A moment after missing by a fraction, Montero collected Ethan White’s errant ball and linked with Rosales, who one-touched a lovely diagonal ball to Fernandez on the back side for an angled finish past the beleaguered Willis.

“Their running out of midfield was pretty good early and caught us,” Olsen said. “But at 1-0, I think we’re okay. The second one hurt us.”

Sensing the outcome and knowing his team will play again soon, Olsen removed Davies and De Rosario early in the second half.

The Sounders secured victory in the 60th minute. Again, Rosales was the trigger, serving a high cross to the back side. Willis made a reaction save on Montero’s header, but Fernandez fired in the rebound from inside the six-yard box for his eighth goal.

United needed 72 minutes to create its first serious opportunity, but Kasey Keller made an excellent save on Joseph Ngwenya’s rising drive. Later, Keller made a splendid stop on reserve Josh Wolff’s effort.

Looking ahead to Wednesday, “Hopefully we will be mentally ready against a team that we should get three points,” De Rosario said of the match against Chivas USA (7-12-10). “One thing we learned tonight is that when it’s coming down to crunch time, any mistake you are going to get punished for. We’ve got to limit our mistakes in the back and capitalize on our chances going forward.”

FIRE 3, CHIVAS USA 2: Dominic Oduro scored in the 85th minute to give short-handed Chicago a victory in Bridgeview, Ill.

RED BULLS 1, FC DALLAS 0: Luke Rodgers scored in the 36th minute and visiting New York hung on to snap an eight-game winless streak.

TORONTO FC 2, RAPIDS 1: Danny Koevermans scored twice in the second half to give host Toronto FC a win over Colorado.

DYNAMO 2, EARTHQUAKES 1: Second-half substitute Will Bruin scored in the 79th minute to send host Houston its first win in nearly a month.

UNION 1, CREW 0: Sebastien Le Toux scored his team-leading seventh goal in the 32nd minute, and host Philadelphia snapped an eight-match winless streak with a victory over Columbus.

REAL SALT LAKE 1, SPORTING KANSAS CITY 0: Nat Borchers scored on a header in the 54th minute and Real Salt Lake won its fourth straight match.

— Associated Press