WASHINGTON — Late drama left D.C. United despondent on Wednesday night as the Columbus Crew staged a stunning comeback to advance to the US Open Cup final with a 2-1 victory at RFK Stadium.

United took an early lead through Pablo Hernandez, but Marc Burch deflected Andy Iro’s shot past Bill Hamid in the 89th minute to send the match to extra time, where Guillermo Barros Schelotto rifled a penalty home for the game-winner on a hot night in the nation’s capital.

DC striker Danny Allsopp nearly created the game’s first goal out of sheer hustle after a mix-up between Chad Marshall and Crew goalkeeper Andy Gruenebaum in the early going. But United broke through soon after, earning a penalty kick through another bit of dodgy defending by the visitors in the 12th minute.

What should’ve been a simple clearance out of the Columbus box suddenly wound up at the feet of Hernández, who went to ground in the box under a clumsy challenge from Iro, and referee Chris Penso did not hesitate to point to the spot. Hernández dispatched the penalty himself with a clinical finish into the lower right corner, his third goal of the tournament.

Keyed by Eddie Gaven’s energetic runs along the left flank, Columbus responded, carving out several half-chances as target man Steven Lenhart looped two headers wide of Hamid’s net and Schelotto probed the United defense with a few free-kick deliveries.

Yet the game’s rhythm soon petered out in the face of some increasingly antagonistic challenges from both sides. Devon McTavish, Dejan Jakovic and even Crew coach Robert Warzycha earned yellow cards as the teams struggled to come to grips with Penso’s interpretation of the rules.

Tempers did not ease as the second half unfolded and Penso found himself at the center of the action in the 59th minute. Hernández tangled with Danny O'Rourke at midfield and kicked out at the Crew defensive midfielder as from a prone position, prompting an enraged O’Rourke to face up to the Argentinean after landing what looked like an angry stomp.

But Penso, under the advice of fourth official Jeff Gontarek, produced a red card for Hernández and only a yellow for O’Rourke, drawing a cascade of boos from the irate home fans.

Eager to grind down his tiring opponents, Warzycha brought on Dilly Duka and Jason Garey in a double substitution but it was the hard-working Gaven who sniffed out the next chance for his side in the 71st minute. Chasing down a through ball into the DC box, Gaven seemed inches away from an equalizer, only to be denied by a massive save from Hamid.

United coach Ben Olsen brought on another defender in the shape of Jordan Graye, pushing Andy Najar further up the field in a lone striker role, and the young Honduran’s relentless efforts kept the Crew on the back foot despite their numerical advantage. Najar forced an awkward parry out of Gruenebaum with a knuckling shot in the 79th minute as DC did their best to kill off the clock.

Yet they fell one minute short. A high ball into the DC box fell for Iro at the edge of the 6-yard box, and the English-born defender held off Jakovic before poking a low drive that Marc Burch deflected past Hamid into his own net to draw Columbus level in the 89th minute.

United hearts sank, only to flutter seconds later as McTavish collected a long pass and slalomed across the top of the Crew box before slotting an excellent ball into Najar’s path, leaving him with only Gruenebaum to beat – but Najar tapped his shot wide right.

That sent the match into overtime, where the visitors monopolized possession and earned a spot kick of their own in the 98th minute. It was created by Lenhart’s sterling work along the endline as he maneuvered past Burch and surged deep into the box, where he was tripped by Carey Talley.

Though the sequence ended with a teammate firing his cross into the net, Penso blew for a penalty instead and gave Talley a caution. Schelotto hammered the ensuing PK into the roof of the net for a 2-1 Crew lead.

Warzycha’s side were almost home and dry, yet they were fully exposed by yet another counterattack at the end of the first period. Santino Quaranta and Najar combined to present Jakovic with a gilt-edged chance at the far post, but the Canadian blazed his effort over the bar from close range as the crowd groaned.

Extra-time sub Jaime Moreno thought he’d earned another penalty after the break when Frankie Hejduk and Duka barged him over in the Crew box following some clever footwork. But Penso waved play on and the Black-and-Red failed to muster any late heroics of their own, sending the Crew on to the final.