Teal Bunbury (No. 9), right, of Sporting Kansas City celebrates his goal with Kei Kamara (No. 23) during a 2-1 victory over D.C. United at Livestrong Sporting Park in Kansas City, Kan. (Ed Zurga/GETTY IMAGES)

D.C. United was under merciless pressure for 90 lopsided minutes Saturday night, and if not for the right post, the crossbar and goalkeeper Bill Hamid’s reflexes, the outcome would have been decided by early in the second half.

Inevitably, United’s good fortune soured, resulting in a 2-1 loss to Sporting Kansas City in front of 20,439 at sold-out Livestrong Sporting Park.

Graham Zusi, a former University of Maryland star, shattered a 1-1 tie in the 63rd minute as short-handed United (11-8-3) dropped its fourth straight on the road and missed an opportunity to strengthen its playoff position in MLS’s Eastern Conference.

Teal Bunbury and United rookie Nick DeLeon traded goals 10 minutes apart in the first half, but first-place Sporting (13-7-4) was far superior against a D.C. team playing without 2011 MVP Dwayne De Rosario for the first time this season.

“They were better than us in every aspect,” United Coach Ben Olsen said. “Bill did his job, but everyone else, there was more they could’ve done.”

United was without De Rosario (shoulder), forwards Maicon Santos (toe) and Hamdi Salihi (virus), and defenders Daniel Woolard (concussion) and Robbie Russell (foot).

Aside from two superb runs by Andy Najar, including the buildup to DeLeon’s goal, United’s attack failed to manufacture quality chances. De Rosario’s absence had much to do with it, but playmaker Branko Boskovic didn’t make any plays before leaving at halftime with a knee ailment, and the forwards received little service.

“We were too careless,” midfielder Perry Kitchen said. “Defensively we would do the work and win it, but to give it back right away, you can’t keep doing that over the course of the game.”

Kansas City had almost 70 percent of possession in the first half and 63 percent overall. Hamid thwarted several opportunities; two first-half shots struck the post; and Zusi hit the crossbar on a half-volley shortly after intermission.

“It’s only a matter of time when you are sitting back like that,” forward Chris Pontius said.

Sporting began to dictate terms 10 minutes into the match. After Hamid tipped away Aurelien Collin’s header, Bunbury shook off Pontius’s mark and nodded Zusi’s corner kick into the left side.

Kei Kamara whistled a 19-yarder fractionally wide and Hamid reacted at the last instant to touch Zusi’s one-timer off the post.

United answered in the 23rd minute. In his first game since returning from Honduran Olympic duty, Najar made an artful run that ended with a tight cutback. He then floated the ball toward DeLeon on the back side. DeLeon got the best of Michael Harrington — and might have guided the ball down with his arm — before sweeping it past Jimmy Nielsen for his first goal since April 22.

United was saved by the post again on Paulo Nagamura’s low bid. Two minutes later, Hamid reacted to his right to stop Michael Thomas’s header.

Zusi struck 18 minutes into the second half, settling Kamara’s cross and lashing an angled eight-yarder under Hamid. Poor marking in transition had left Zusi alone on the far side.

“It looked like we fouled up some marks and we’re not real organized there,” Olsen said. “But it was the whole buildup.”

There was plenty of time for an equalizer, but without De Rosario or sustained possession, United was harmless. Since a four-game winning streak vaulted it into first place, D.C. has dropped four of six and will now have to fend off Montreal and Columbus to secure a postseason berth.

“You can’t expect to defend for 90 minutes,” Kitchen said, “and come out with a result.”