WASHINGTON -- The MetroStars lost two key players, another matchup with D.C. United and may have lost their grip on a playoff berth.

Ali Curtis scored in the 87th minute as United kept alive their postseason hopes with a 2-1 victory, their second over the MetroStars in three days.

The Metros failed for the second time to nail down a playoff berth. And they will not have forward Clint Mathis and goalkeeper Tim Howard for the regular-season finale against New England after both players received red cards.

Marco Etcheverry set up the go-ahead tally, sending a clinical pass to Curtis on the right side of the field from tight space near the center circle. Curtis controlled the ball on the break and got around Howard and defender Nelson Akwari before putting home the game-winner.

Disaster struck the MetroStars in the third minute of stoppage time as Howard was shown a red card for an illegal challenge on forward Roy Lassiter just outside the penalty area. Curtis threatened to carry the ball in on the right side before shifting the attack to a wide-open Lassiter on the left. Howard charged out to take away the ball from Lassiter, making contact outside the box.

Backup Paul Grafer stepped in and made the save on Etcheverry's free kick, but United claimed the Atlantic Cup after taking the regular-season series.

The MetroStars grabbed the lead in the sixth minute on a goal by Rodrigo Faria. But Mathis was ejected in the 30th minute for stepping on the back of midfielder Jose "Chino" Alegria.

Bobby Convey tied it in the first minute of first-half stoppage time, coolly finishing a pass from Petter Villegas.