In the 68th minute of D.C. United’s 1-1 preseason draw with the third-division Charleston Battery on Wednesday, Ben Olsen summoned his top-choice players. Ten of them pulled on jerseys, fell into line behind one another like a military exercise and awaited entry.

That was the group that started the Carolina Challenge Cup opener last weekend and will probably start this weekend’s tournament finale as well as the MLS opener March 8 against the Columbus Crew at RFK Stadium.

The mass substitution yielded Davy Arnaud’s goal four minutes later, but with time melting away, United conceded the equalizer. Goalkeeper Joe Willis misplayed a corner kick, resulting in another corner, which led to Drew Ruggles’s goal on the last touch of the match.

“It was a comedy of errors toward the end,” Olsen said. “We have got to clean that stuff up. . . . The second group brought the right energy, the right movement to the game and got the goal. There is no excuse to let them back in the game.”

United (1-0-1 in the four-team tournament) will face the Seattle Sounders (1-0-1) for the championship on Saturday.

Olsen will not savor Wednesday’s performance. A young starting lineup failed to seize the initiative, and with the exception of first-round pick Steve Birnbaum’s work in central defense, Kyle Porter’s runs and Andrew Dykstra’s superb foot save, United labored.

“The first half looked like a young group playing against low-pressure defense,” Olsen said. “You have to have ideas. You have to move the ball quick. You’ve got to get it off your feet. You’ve got to be dynamic. You’ve got to move off the ball.”

The lineup included midfielders Victor Munoz and Reuben Ayarna, who are vying for final roster slots, and three homegrown players: defenders Conor Shanosky and Jalen Robinson and forward Michael Seaton.

Robinson, a right back, departed late in the first half with a hamstring injury that might sideline him for weeks, Olsen said.

With the addition of Collin Martin and Christiano Francois, the youthful unit showed improvement early in the second half. But until the first-tier players entered, United did not threaten the Battery (0-1-1).

Midfielder Luis Silva served a 30-yard free kick that Arnaud redirected into the far corner. Later, forwards Eddie Johnson and Fabian Espindola failed to finish prime opportunities in the penalty area.

Charleston, which plays in the USL Pro division, then drew even before the small gathering at misty Blackbaud Stadium.

United notes: Richard Motzkin, Johnson’s agent, said he is “having good conversations” with United concerning a new contract. Johnson’s deal does not expire until the end of the season, but, as part of the agreement in acquiring him from Seattle, the club has offered a pay raise. . . .

Seaton, 17, was named to the Jamaican national team roster for friendlies against Barbados on Sunday and St. Lucia on Wednesday. . . .

In Wednesday’s first game, Seattle and the Houston Dynamo (0-1-1) played to a 1-1 draw. Brad Davis scored in the 14th minute for Houston before Obafemi Martins equalized in the 44th.