Whatever the reason, after being flummoxed for a half by the energetic visitors, RSL (14-10-4) finally grabbed the game early in the second half thanks to a goal by Will Johnson and snapped a four-game winless streak with a 1-0 victory.
"It's always difficult for the guys," said RSL coach Jason Kreis about the conditions that led to the victory. "It can be hard to stay focused. It can be hard because there are so many communications of when you are going to start. All in all, I thought they handled it pretty well and we saw an exciting game tonight."
The win keeps the pressure on Seattle, which had been tied with RSL for second in the Western Conference. The Sounders play Sunday.
Kreis called the three points won by RSL critical.
"I told the guys that yesterday," he said. "We have three home games remaining, now we have two. There can't be anything less than the maximum points in those games to give ourselves the best possible chance to not end up in the last two playoff spots, which we think would put us in dire straits to have a chance to succeed in the playoffs."
Johnson's third goal of 2012, coming in the 49th minute, was set up by a series of steps right out of "Dancing With the Stars."
It began with a quick touch inside the 18-yard box from Javier Morales to Ned Grabavoy, who back heeled the ball to Paulo Junior, waiting on the end line.
Junior's looping pass nicked a United defender, depriving the RSL forward of an assist. But Johnson, camped on the goal line, drove the deflection past United keeper Bill Hamid.
"The ball just sat up there nicely for me, stuck my head in there, was lucky to get on the end of it and knocked it into the back," Johnson said. "The most important thing from the game, though, was the shutout. Every time we shut out a team, it gives us a good chance to win the game."
From that point on, Real sent wave after wave at the D.C. goal. That Salt Lake didn't add more goals had more to do with unlucky deflections than United's (12-10-5) defense.
A few minutes after Johnson's header, RSL nearly doubled the score. However, a foul on RSL's Alvaro Saborio negated Kwame Watson-Siriboe's creative turn-and-shoot inside the 6-yard box.
As the game began, finally, D.C. United certainly didn't resemble a team that was in the midst of a grueling schedule.
United gave Real Salt Lake all it could handle and at times more in a scoreless first half.
"I think the guys were playing with angst in the first half," Kreis said. "We often put a lot of pressure on ourselves with the way we perform in the beginning of matches."
RSL was let off the hook in the 28th minute when United forward Dwayne De Rosario banged a long-range shot off the post.
Also, United forward Chris Pontius twice worked his way into the 18-yard box only to misfire wide.