HARRISON, N.J. - A slightly hobbled Fernando Aristeguieta placed the ball on the field and took a few steps back, readying himself for the Union's fifth penalty shot.

He looked as if he could barely stand.

Having not played for a month and a half due to an ankle injury, Aristeguieta made a bold move at the end of overtime as the Union headed to PKs with the New York Red Bulls in a U.S. Open Cup quarterfinal match yesterday evening.

"I went to the coach and said that I want to shoot the fifth [shot]," Aristeguieta said after the game. "Usually I try to take the first one to get out of it, but this time I went and told him that I wanted the fifth one to kill it."

The 23-year-old Venezuelan fired the ball into the upper-left corner of the net while Red Bulls goalkeeper Luis Robles dove in the opposite direction, giving the Union a 1-1 (4-3) victory; the team's second in a row at Red Bull Arena.

The Union took a 1-0 lead thanks to a shorthanded goal by midfielder Eric Ayuk in the 55th minute. But a late goal in the third minute of extra time by Red Bulls midfielder Lloyd Sam sent the game into overtime.

Aristeguieta was poised to play a big role yesterday due to the absence of leading scorer C.J. Sapong, who received a red card against D.C. United in the Union's last Open Cup game.

But, after Conor Casey got a red card in the 41st minute yesterday for tripping Red Bulls defender Connor Lade, the Union was forced to play a man down for the rest of the match, delaying Aristeguieta's entry until the 90th minute when he checked in for Ayuk.

"That wasn't really the game plan of how we wanted to use him," Union head coach Jim Curtin said of Aristeguieta. "I wanted to use Conor about 45 [minutes] and then Fernando 45 but, again, everybody has a plan until you get punched in the mouth, and things change quick and we called upon Fernando for probably a little more time than we would have hoped.

"He was gassed and exhausted but had enough legs to step up and be a man and take the fifth spot."

As soon as Aristeguieta's game-winning penalty shot hit the back of the net, his eyes turned toward his goalkeeper, John McCarthy, who recorded a season-high nine saves in the match, not to mention a pair of clutch saves in PKs that set up Aristeguieta's big moment.

"Normally when you're going to take a PK, you already have the side, but this time I swear I changed it like eight times," Aristeguieta said. "But once the ball is in, my first [thought] goes to John because he's the real hero."

McCarthy has been a revelation in net for the Union in place of usual starter Brian Sylvestre, who is ineligible due to Cup ties with the Carolina RailHawks. McCarthy has been especially impressive throughout the Open Cup, making some huge saves on PKs to beat Rochester in the opening round, and putting up a then-season-high five saves in a round-of-16 win over D.C. United.

The 23-year-old Philadelphia native, who played at La Salle University, was largely untouchable for 120-plus minutes despite a Red Bulls' attack that produced 34 attempted shots (10 on goal) and 14 corner kicks.

His lone blemish yesterday was Sam's goal.

"I just thought that kind of sucked, I mean, there's 30 seconds left in the game," McCarthy said. "But we've been there before, a man down, like we had the same exact experience against D.C. United, so we just had to know it was literally a mental grind, that's all it was."

Despite being outshot by 24 attempts and maintaining possession of the ball for just 32 percent of the game, the Union dodged many a bullet as they grinded out a tough win against a big Eastern Conference rival.

"I'd say it's got to be the biggest win in the club's history all circumstances included," Curtin said. "This tournament is about surviving and advancing. That's all that matters, and we're on to the next game."

The Union will face the winner of tonight's game between the Chicago Fire and Orlando City in next month's Open Cup semifinals.

On Twitter: @@tom_reifsnyder