WASHINGTON, DC - MARCH 1: Queretaro forward Angel Sepulveda (15) slides and steals the ball away from D.C. United midfielder Nick DeLeon (14) during the first half of the Champions Cup game between the D.C. United and Queretaro at RFK Stadium on Tuesday, March 1, 2016. (Photo by Toni L. Sandys/ The Washington Post) (Toni L. Sandys/The Washington Post)

D.C. United began the night in a tight spot. Four minutes into Tuesday’s match against Queretaro, United put itself in an even tighter one.

By conceding an early goal to its Mexican opponent, United lost all hope of advancing to the CONCACAF Champions League semifinals and, for all practical purposes, rendered the last 86 minutes a training exercise for Sunday’s MLS season opener against the Los Angeles Galaxy.

Ahead by two goals after last week’s first leg at home, Queretaro struck first in front of 10,790 at RFK Stadium and, from there, happily accepted a 1-1 draw for a 3-1 aggregate victory.

Julian Buescher, a first-round draft pick from Syracuse, scored for United in the 84th minute on a magnificent shot from 30 yards. United, though, would have had to score three more times to continue on in the tournament, which features clubs from North and Central America and the Caribbean.

“They are two very good preseason games to prepare us for the MLS season,” Coach Ben Olsen said. “I’ve asked the guys to take away and learn some of the lessons from the two games, but also to put it to bed and get excited about the MLS season. We’re 0-0-0. Losses are tough, but it’s over.”

A week after an encouraging performance at altitude against an in-season foe, United was sloppy at the start on Tuesday, as Angel Sepulveda scored in the fourth minute to increase Queretaro’s overall advantage to 3-0.

Sepulveda’s goal rekindled unkind memories from 2015, when United allowed a batch of early goals in league play.

“We shot ourselves in the foot,” left back Taylor Kemp said. “We knew we couldn’t give up a goal. We gave one up in [four] minutes. It makes it really easy for them.”

In the first leg, United kept its shape and managed the match for 70 minutes before allowing two goals, the first coming on a sensational strike by Yerson Candelo. In the return leg, D.C. crumbled right away.

Antonio “Sinha” Naelson evaded Taylor Kemp’s challenge on the right wing and swung a high cross into the penalty area. Both Steve Birnbaum and Sean Franklin drifted toward Edgar Benitez on the back side. Neither got there. Benitez headed the ball back to the unmarked Sepulveda for a nine-yard one-timer into the left corner.

“All of a sudden, game’s over,” Olsen said. “Just like that.”

The game wasn’t over, in reality, but the series very much was. Beyond the aggregate goal count, Queretaro had also secured the away-goal tiebreaker.

“It’s pretty unacceptable to give up a goal that early,” Birnbaum said. “It was devastating.”

Olsen had tinkered with the lineup, dropping attacker Luciano Acosta, who had performed well in the first leg. As agreed upon when he signed three weeks ago, Acosta returned to Argentina after the match in Mexico in order to pack up his family for a permanent move to Washington. He did not report back to the District until the weekend, and the absence had left him ill-prepared to start again.

He ended up entering early in the second half. By then, the outcome of the series had been settled.

United did make the effort. By and large, though, United performed like what it was: a team that had opened training camp 5½ weeks ago and played one serious match since November. With chemistry and rhythm in the developmental stages, most everything United mustered came from effort and resolve.

In the 55th minute, Patrick Nyarko drew a penalty kick. Rolfe’s bid, however, lacked direction and polish, allowing Tiago Volpi to slide to his right and block the shot as if it were a routine play.

Still gaining fitness after missing parts of preseason with tendinitis, Rolfe, United’s leading scorer in 2015, left in the 59th minute. He came off at a similar point in the first leg, as well.

Buescher took advantage of a second-half appearance by pumping a swerving shot into the upper right corner.

“We’ve got a lot to look forward to,” Olsen said. “We’ve got a lot of great pieces. It’s up to me to figure out which ones are best with each other and mold this group into a very competitive team, which I think it can be.”

United note: The Scottish Sun reported former D.C. midfielder Perry Kitchen will sign with Hearts, which is in third place in Scotland’s top-tier league. Kitchen’s contract with United expired Dec. 31, and he declined an offer that would have more than doubled his MLS base salary.