D.C. United's Lewis Neal celebrates the games lone goal late in the first half against Real Salt Lake. (Matt Gade/Associated Press)

D.C. United will complete the 2013 campaign this month with one of the worst records in MLS history. It will also end the year with a shiny addition to its trophy case.

The incongruous scenario unfolded Tuesday night as United continued to set aside months of atrocious league results and won the U.S. Open Cup title, a 1-0 stunner against Real Salt Lake before 17,608 at Rio Tinto Stadium.

The tournament — in its 100th year and involving teams from amateur to professional — does not carry the weight of MLS Cup, but for a D.C. side with a 3-21-6 record in the regular season, it meant everything.

“If there’s one thing we did a good job of this year was sticking together,” Coach Ben Olsen said. “The wheels never fell off — and a lot of times it was close. When you go through this much turmoil, it’s tough to stay together.”

Midfielder Lewis Neal, sidelined most of the year with groin injuries, scored late in the first half — the club’s only shot on goal over 90 minutes — and United absorbed unrelenting pressure after intermission to upset the MLS Cup contenders.

With its third Open Cup title, United claimed $250,000 in prize money (shared among the players) and a berth in the 2014-15 CONCACAF Champions League, featuring clubs from North and Central America and the Caribbean. D.C. has not competed on the international stage since 2009.

“I am not going to say it’s erased all the losses,” forward Chris Pontius said during a raucous locker room celebration, “but it’s special.”

United has failed to win any of 16 regular season away games. But in the Open Cup, it triumphed at Chicago in the semifinals in August and defeated a Real team playing its fifth consecutive tournament match at home.

United’s performance stirred memories of last fall’s run to the Eastern Conference finals, when a team with clear limitations found a way to win.

The idea Tuesday was to disrupt Real’s superior possession – the hosts hoarded nearly 70 percent of it — with a disciplined, measured approach.

Susceptible to early-game breakdowns all year, United kept cool. United would have been content to remain on level terms at halftime, but with intermission approaching, D.C.’s patience paid off.

John Thorrington worked the left side and crossed into the heart of the penalty area. Defender Carlos Salcedo knocked the ball down but not out of danger. Neal met it in stride and laced a 12-yard one-timer beyond Real goalkeeper Nick Rimando’s reach to the far corner.

“I hung back and hoped something would spill out,” said Neal, an Englishman who failed a tryout with Real in 2012 and played a pivotal role in United’s success last year. This season’s injuries have allowed him to make just six league appearances.

Real turned up the heat after the break. Sebastian Velasquez cranked a 20-yarder off the crossbar in the 59th minute. Bill Hamid deflected Alvaro Saborio’s angled bid in the 81st.

Real set siege on the penalty area. United had a chance to seal the outcome, but substitute Conor Doyle’s breakaway was interrupted by Rimando. United howled for a red card; Rimando received yellow.

After six harrowing minutes of added time, including a last-gasp effort by Real that appeared to hit the crossbar, United celebrated an unlikely championship.

Said captain Dwayne De Rosario: “I’m just so happy we stayed together and accomplished something — something huge.”

Regular season play resumes Friday night against Chicago at RFK Stadium.