Tampa Bay blows late 2-1 edge to remain only one point ahead of New England in the East.
The Mutiny let another one slip away Sunday and, with 10 games left in the MLS season, such generosity could cost the club a playoff spot.
United reserve A.J. Wood headed home a Marco Etcheverry corner kick for a 2-2 tie in the 85th minute, then Eastern Conference leader D.C. United prevailed 3-2 in a shootout to earn one point.
Tampa Bay has an extremely tenuous hold on the East's fourth and final playoff spot at 9-13 with 19 points, two behind the Miami Fusion (9-13) and one ahead of the New England Revolution (8-12), which has two games in hand.
Eleven of Tampa Bay's 13 losses have come after permitting a goal in the final 15 minutes.
"Obviously, you're up 2-1 with four or five minutes to go, the emphasis has to be on doing well, not giving up a goal," goalkeeper Scott Garlick said. "Everybody knows it."
D.C.'s tying goal came after a Mutiny giveaway in the top right of its penalty area. The goal is the eighth Tampa Bay has allowed in the final 10 minutes of a game.
Mutiny defender Dominic Kinnear headed a United blast over the end line to set up the equalizer. Etcheverry put the ball on the head of A.J. Wood, 8 yards in front of the far post.
Wood, who entered only six minutes earlier, drilled his header low into the left corner, his fourth tally in his past five outings.
In the shootout, Tampa Bay's Steve Ralston and Josh Keller scored in the first and third rounds, respectively. United goalkeeper Tom Presthus saved the Mutiny's final two attempts by Raul Diaz Arce and Jorge Salcedo. Wood, Roy Lassiter and Jaime Moreno were successful for United.
In 11 of Tampa Bay's 13 losses, the Mutiny led sometime during the game or the score was tied with 15 minutes to go.
"Despite the tie going into the last few minutes, we still created a couple chances, so there's a lot of positives to take out of this game," Mutiny coach Tim Hankinson said. "We showed we can play offensively, but we have to do better when we've got a chance to close the coffin."
In the 16th minute, United took a 1-0 lead after Moreno pushed a pass to Lassiter just inside the top of the box. Lassiter sidestepped Garlick's advances and lofted a pass to Etcheverry who sent a soft 7-yard header into the left top corner before Garlick could recover.
The Mutiny tied it in the 40th minute, beginning with Ralston's quick restart to Carlos Valderrama, who fed Musa Shannon for an 8-yard header that hopped once into the left corner.
Steve Trittschuh positioned himself to be the hero when he fired a header home for a 2-1 lead in the 51sth minute.
Kinnear started the sequence taking a long Mauricio Ramos pass and carrying into the right corner before crossing to the near post, where Shannon lifted it back to Trittschuh. From the air, the defender nailed his shot 6 yards into the top right corner.
In the 73rd minute, however, Trittschuh was given a red card for taking down Moreno from behind. The United pressed forward, attempting to exploit the man advantage.
In the time between his goal and his expulsion, the Mutiny created some good scoring chances and twice was stopped from increasing the lead by reaction saves by Presthus.
"Some will call that a red card in this league. Some won't," Trittschuh said. '"So you're playing on a fine line. Some refs will call that a yellow (card). I feel like I let my teammates down. We fought back to take the lead 2-1 and I let them down."
The red card to Trittschuh and a yellow to defender Chad McCarty _ which gave him 21 caution points _ means both will be suspended for Friday's home match with Western Conference leader Colorado, a game that also serves as a U.S. Open Cup round-of-16 contest.
The club is left to hope recently signed central defender Joseph Addo can obtain his work permit in time.
_ Information from the Associated Press was used in this report.
A Mutiny player has been ejected six times and the club is 1-5 in those games. The aggregate score in the opponents' favor: 8-7 before the ejections, 13-5 after them.
Opponent Score Ejected Final
DC United 2-0, DC Scott Garlick 5-2 DC
Miami 1-1 Carlos Valderrama 2-1, Miami
Los Angeles 1-1 Garlick 4-2, L.A.
Kansas City 2-2 Steve Trittschuh 4-3, K.C.
Columbus 1-1 Dominic Kinnear 3-2 (SO), T.B.
DC United 2-1, T.B. Trittschuh 3-2 (SO), DC