The ball trickled to Montreal's Ignacio Piatti on the left side of the goal, and Union goalie Brian Sylvestre was on the ground near the opposite post.

But just as Piatti went to tap the go-ahead goal into a wide-open net, the midfielder lost his footing. He fell to the grass as the ball, and two points in the standings, rolled away. Sixteen minutes later, the final whistle blew in a 2-2 tie between the Union and Impact at PPL Park on Saturday.

A steady downpour soaked the field and thinned the crowd, and the game was defined by missed opportunities for both sides. The Union (5-10-4) were given a man advantage after Patrice Bernier's second yellow card and ensuing ejection in the 67th minute. Then the hosts gave that advantage away when midfielder Eric Ayuk was sent off for his second yellow 10 minutes later.

"Credit to our guys, they fought hard," Union head coach Jim Curtin said. "They pushed, they got the tying goal. Then we go up a man, and it feels like we have all the momentum in the world and kind of a roller-coaster night for [Ayuk], a young player who hopefully will learn from this."

Before the Union and Impact (5-6-3) traded goals and red cards in the second half, Ayuk nudged his team ahead, 1-0, with a goal in the eighth minute. Forward C.J. Sapong, who had scored in four consecutive games heading into Saturday, settled a lofted ball and dropped a pass to Ayuk before the midfielder slotted a goal past a sprawling Evan Bush.

The lead didn't last too long, as Piatti slipped past the Union defense and beat Sylvestre in the 28th minute.

After the break, Jack McInerney snuck behind the Union's back line and gave the Impact a one-goal advantage despite being down a man.

In the 76th minute, a clearing attempt popped out to Union defender Fabinho, who ripped a shot through a crowd and right at Bush. The rebound fell at the feet of Maurice Edu, who faked once and slotted the game-tying goal inside the left post.

Then Ayuk left his feet on a tackle, and neither side ever regained a grip on the game.

"The game was 11 vs. 11, and then Montreal was 10," Ayuk said. "I was so disappointed because of the red card."