D.C. United forward Dwayne De Rosario, right, controls the ball against the Chicago Fire during the first half of the Lamar Hunt U.S. Open Cup semifinal last month. (Nam Y. Huh/Associated Press)

A victory in the U.S. Open Cup championship Tuesday would not erase the horrors of D.C. United’s record-threatening regular season. With three victories in 30 matches, the 2013 MLS campaign has inflicted scars that will endure deep into the winter and surely stimulate change.

But soccer worldwide offers second chances. While the league mission remains paramount, cup competition is often salvation for clubs on the skids. The American brand is no exception with the Open Cup, a century-old tournament involving teams from the amateur to full professional levels.

United skidded off course many months ago, but by compartmentalizing its regular season issues and rallying through four rounds of the Open Cup, the club will play for a trophy against Real Salt Lake at Rio Tinto Stadium in Sandy, Utah (9 p.m., GolTV).

The champion will collect a $250,000 bonus and a berth in international competition, the 2014-15 CONCACAF Champions League. United has not performed on the international stage since 2009, reward for winning the Open Cup a year earlier.

“Not many people are giving us a chance in this game,” Coach Ben Olsen said of his 3-21-6 squad hitting the road to face an MLS title contender, “but we have decided we are going to show up anyway.”

United hasn’t shown up for the regular season. One year after finishing with the third-best record and advancing to the Eastern Conference finals, United is flirting with the worst mark in MLS’s 18-season history. (The record for fewest victories is four, accomplished twice.)

In the Open Cup, however, United scraped by its third-division affiliates, the Richmond Kickers, in a penalty kick shootout, then defeated MLS brethren Philadelphia, New England and Chicago. D.C. has scored 20 goals in 30 regular season matches, but eight in the past three cup games.

The regular season gap between cup finalists is not unusual. In May, in England’s prestigious FA Cup, struggling Wigan shocked powerful Manchester City with a late goal, 1-0, at Wembley Stadium. Wigan ended up in 18th place in the Premier League campaign and was relegated to the second tier. (United does not have to worry about relegation; such demotions do not yet exist in the evolving American pro system.)

Some MLS teams take the Open Cup more seriously than others, and when the regular season fell apart early in the summer, United invested more energy and personnel into the tournament. D.C. looked good in each of the past three outings, capped by a 2-0 semifinal victory at Chicago in August. (United has an 0-13-3 regular season road record.)

“I’ve thought about it: Why have we performed well in those games and haven’t translated it into league games?” midfielder-forward Chris Pontius said. “I can’t put my finger on it.”

Whatever the reasons, the Open Cup opportunity has lifted spirits in what has been an otherwise hopeless second half of the season.

“It’s spiraled in a positive while the [MLS] season results have spiraled in the negative,” said Olsen, whose team defeated Real, 1-0, at RFK Stadium in the second game of the regular season.

“It would have been a very tough situation to motivate these guys with nothing to play [for] with 21 / 2 months left in the season. To their credit, they have separated the season and the Open Cup.”

To prepare for the final, Olsen rested his regulars Saturday and fielded almost entirely reserves during a 4-1 loss at Toronto FC, the second-worst team in MLS. Despite being in the heat of a playoff race, Real Salt Lake (15-10-6) did the same, only with the opposite outcome: a 1-0 victory at contending Vancouver.

“It’s a huge, huge opportunity,” United captain Dwayne De Rosario said. “We can finish off what could be — what is — a disappointing year.”