Colorado’s Caleb Folan celebrates his goal in the 38th minute. (Doug Pensinger/Getty Images)

D.C. United had endured the snow and wind, the cold and altitude. It had played with renewed passion and commitment, overcome the absence of five regulars, and when Santino Quaranta scored the equalizer in the 70th minute Sunday, United was in position to sneak out of the frosty Denver suburbs with at least a draw against the defending MLS champions.

“At that stage, I thought we would see the game out and it would be a pretty fair result for us,” goalkeeper Pat Onstad said. “By the time I finished that thought, it was 2-1.”

The Colorado Rapids needed only a minute to reclaim the lead, seizing on United’s mystifying breakdowns, then added two late goals for a 4-1 victory before an announced crowd of 9,857 at Dick’s Sporting Goods Park.

“We work hard to finally squeeze a goal and we just let them off the hook,” said Coach Ben Olsen, whose club has lost two straight since winning the season opener. “We got the tie with 20 minutes left and we should be able to deal with that and at least get a point.”

Instead, the Rapids (3-0) went right back ahead on Jamie Smith’s header. United was deflated, and never seriously threatened again. Caleb Folan scored Colorado’s first and third goals, and Omar Cummings capped the late surge in added time.

“You switch off for one minute – not even one minute; 30 seconds – and you are going to get penalized,” captain Dax McCarty said. “We’re a young team. We have a lot of guys who are very talented but maybe a little naïve in the sense that [they think], ‘Hey, we scored a great goal, we’re outplaying them, and we think we’re pretty good.’”

The Rapids, who have scored at least three goals in six of their past eight home matches, converted all four shots on goal. Onstad, 43, was partly at fault, but his teammates let him down as well.

On the go-ahead goal, Anthony Wallace was given too much time and space on the left sideline to float a long ball into the box. Smith was left unmarked. Onstad decided not to come off his line to challenge Smith, who nodded a 12-yarder into the far side of the net.

Ten minutes later, the Rapids scored on a similar build-up from the opposite flank. Reserve Sanna Nyassi lofted the ball into the box, where Folan beat Rodrigo Brasesco to the header. Onstad was slow to react, and the outcome was secured.

For 70 minutes, United had given a respectable performance without defenders Jed Zayner (hamstring), Dejan Jakovic (red card suspension) and Perry Kitchen (U.S. under-20 national team duty), as well as midfielder Clyde Simms (calf) and forward Charlie Davies (groin).

Rookie forward Blake Brettschneider was eager and active in his debut, and veteran midfielders Quaranta and Branko Boskovic, in their first starts of the season, showed ambition.

United wasn’t bothered by the weather. A day after a record 84-degree afternoon, a storm front plunged over the Rockies Sunday, dropping the temperature into the thirties and producing a snow squall.

Ninety minutes before kickoff, a plow was summoned to clear the inch or two of snow and slush from the field.

To avoid a repeat of last week’s murky start at New England, United emphasized higher energy and quicker ball movement. It was a promising display. When Colorado gained traction, outside backs Chris Korb and Marc Burch extinguished mounting threats.

In the 38th minute, though, the Rapids broke through when Folan, an English league veteran in his first MLS season, challenged Brasesco with deft footwork on the right side of the box. The D.C. defender bit to the outside, allowing Folan to lash a 12-yard, left-footer beyond Onstad’s reach.

Less than two minutes later, Brettschneider’s angled bid missed the far corner by maybe a foot.

United’s persistence paid off when Korb, a rookie, served a superb ball to Quaranta for a 10-yard volley. The goal should’ve turned the match in United’s favor. Instead, D.C. dozed off and was left emotionally shattered.

Said Onstad: “We were all reminding each other to be smart and concentrate, but it happened, and from there, it snowballed.”