United's Joseph Ngwenya is beside himself after not getting a call that would have resulted in a penalty kick. (Doug Kapustin/for The Washington Post)

Nothing had gone D.C. United’s way Saturday night, what with another goal conceded off a dead-ball sequence, a shameful first half performance, starting forwards Charlie Davies and Josh Wolff departing before intermission with injuries and a seemingly sure penalty kick ignored by the referee.

So midway through the second half, United warmly welcomed a favorable call by Terry Vaughn, who probably should’ve whistled a foul on D.C.’s Chris Pontius or allowed play to continue.

Pontius converted the ensuing penalty kick in the 62nd minute, offsetting Drew Moor’s first-half goal, as United tied the Colorado Rapids, 1-1, in front of 12,499 at RFK Stadium.

The result extended United’s unbeaten streak to three matches but given the dodgy start, it was hardly a satisfying outcome.

“Not happy with one point, happy that we battled back, but the way we dealt with that first 45 [minutes] was not good enough,” Coach Ben Olsen said.

United's Santino heads the ball to a teammate while being defended by Colorado's Drew Moore. (Doug Kapustin/FOR THE WASHINGTON POST)

It was an especially disappointing evening for Davies, the league’s leading scorer entering the night, who was hoping to make a favorable impression on U.S. national team coach Bob Bradley. Preparing to finalize his roster for a friendly against World Cup champion Spain and the CONCACAF Gold Cup, Bradley was in attendance to evaluate Davies and others.

Davies, hoping to reclaim a U.S. roster spot after his extraordinary comeback from injuries suffered in a 2009 car accident, didn’t show well before departing in the 34th minute with a hamstring injury. Ten minutes later, Wolff left with a groin ailment.

The Rapids (4-3-3) were quicker in the early moments and forced D.C. (3-4-3) to chase the game. United responded in a robust manner: Davies was a whisker offside, voiding his apparent goal; Wolff’s header off Dax McCarty’s free kick narrowly missed; and Davies’s heavy touch into the box spoiled Wolff’s set-up.

Colorado seized the lead in the 23rd minute on a set piece — a United frailty throughout the spring. “It feels like a broken record,” McCarty said. “It’s frustrating.”

Jamie Smith served a free kick into the heart of the penalty area. United failed to clear — the ball appeared to strike defender Dejan Jakovic — and Moor pounced on the deflection to finish with a sliding effort from six yards.

The situation deteriorated for United as Olsen had to replace his front line before halftime. Santino Quaranta and Joseph Ngwenya entered.

Just before the break, United made its case for a red card to Moor, who had upended McCarty breaking into the clear. Vaughn wasn’t swayed and retrieved his yellow, drawing vociferous protest.

D.C. United's Andy Najar gets run over by Colorado's Jeff Larentowicz. (Doug Kapustin/FOR THE WASHINGTON POST)

In the second half, United enjoyed an abundance of possession and exhibited renewed energy and commitment but lacked that special ingredient to swing the match.

United howled for a penalty kick when Ngwenya, who had collected Quaranta’s outstanding high ball, was clipped by Jeff Larentowicz. Vaughn allowed play to continue. “For sure, I got fouled,” Ngwenya said.

Five minutes later, Vaughn was back in the spotlight when he awarded United an undeserved penalty kick. On a forceful run to the edge of the box, Pontius lowered his shoulder and initiated contact with right back Kosuke Kimura. Both players tumbled. Vaughn pointed to the penalty spot.

“Out of all the calls, mine was the one where it could go either way,” Pontius said. “I’m not diving; there’s contact. But I really don’t know what’s being called” on Ngwenya’s plea.

With Davies, United’s penalty kick specialist, unavailable, Pontius converted into the left side for his third goal.

Commenting on Vaughn’s overall performance, Olsen said: “I think he had a very bad night.”

The remainder of the match was marred by physical encounters, injury stoppages and disputes with Vaughn. Olsen went for the win in the 80th minute, replacing Simms with Fred, but a late threat fizzled and the sides escaped the rain with a point apiece.

“To get out of here with a tie when you’re down is obviously a positive, but you never want to tie at home,” McCarty said. “You always want to win.”

United notes: Defender Conor Shanosky leaves Sunday for U.S. under-20 national team duty in France. . . . United will host Dutch power Ajax in a friendly next Sunday.