THERE WAS a downtrodden tone around PPL Park for most of last night. Between the pouring rain and C.J. Sapong being sent off in the 24th minute after a questionable straight red card, things were not looking good for the Union.

The weather got better as the night went on, following a delay of more than 40 minutes, and so did the Union. Eric Ayuk and Fabinho scored second-half goals, leading the Union to a 2-1 come-from-behind win over D.C. United in the Lamar Hunt U.S. Open Cup, despite being down a man for more than two-thirds of the match.

"It is a mistake by the referee, for sure," Union manager Jim Curtin said of Sapong's red card. "It wasn't a contentious game. It wasn't heated. There wasn't tackles that you would say, 'That was a dirty tackle.'

"He was very quick to go to the red. In soccer now, it is becoming too easy to be kicked out of the game," Curtin added. "That's the simplest way I can put it. There's a million different variables that go into it. He doesn't extend the elbow, he jumps as high as he can. It was nothing malicious. I think it was a mistake by the referee. Mistakes happen, I understand that."

The Union moved past the mistake and the rest of the adversity in showing a lot of grit and determination to come back.

"I thought our group took a big step tonight, and, in a lot of ways, it is the most proud I am since I've been the head coach, because games like this bring groups together," Curtin said.

After a tap-in Ayuk goal in the 51st minute tied the game, the teams played a stalemate for much of the second half. The Union had plenty of chances to take the lead, but did not break through until late.

Fabinho took the ball up the left side of the pitch, used a give-and-go with Cristian Maidana and beat United goalkeeper Andrew Dykstra high to give the Union the lead in the 79th minute that it would not relinquish.

Fabinho came into the game late for Andrew Wenger, who Curtin thought was fatigued. Wenger had a great chance in the second half, but clanked a clear putaway off both posts before being cleared by D.C.

Despite being down a man, the Union seemed to outplay United for most of the match. D.C.'s only goal came on a broken play in the 27th minute, when the ball ended up in the middle of the box in front of Jario Arrieta. He put it past John McCarthy, who could not do anything but watch.

Other than that, the Union controlled the tempo and did not allow many scoring chances for United, which, granted, did not play all of its usual starters. McCarthy was not really tested very much all night.

"You can talk about D.C. playing their second group, and this and that, but we've been through a lot of adversity tonight," Curtin said. "To play shorthanded from the 25th minute is very challenging."

The win advances the Union to the quarterfinals against the winner of the New York Red Bulls and the New York Cosmos, who play tonight at 7:30.

The quarterfinal will take place July 21 or 22.